diff --git a/maidroid_core/cores/farming.lua b/maidroid_core/cores/farming.lua
index 991a28d..254c699 100644
--- a/maidroid_core/cores/farming.lua
+++ b/maidroid_core/cores/farming.lua
@@ -22,14 +22,16 @@ local target_plants = {
 	"farming:wheat_8",
 }
 
+local VELOCITY = 3
 local SEARCHING_TIME_INTERVAL = 20
-local MOWING_TIME = 5
+local MOWING_TIME_INTERVAL = 20
+local PLANTING_TIME_INTERVAL = 5
 local TO_TARGET_DISTANCE = 1.25
 
--- has_seed_item reports whether maidroid has seed items.
-local function has_seed_item(self)
+-- has_seeditem reports whether maidroid has seed items.
+local function has_seeditem(self)
 	local inv = self:get_inventory()
-	local stack_list = inv:get_list("main")
+	local stacks = inv:get_list("main")
 
 	for _, stack in ipairs(stacks) do
 		local itemname = stack:get_name()
@@ -45,112 +47,187 @@ local function is_plantable_place(pos)
 	local node = minetest.get_node(pos)
 	local lpos = vector.sub(pos, {x = 0, y = -1, z = 0})
 	local lnode = minetest.get_node(lpos)
-	return node.name == "air" 
+	return node.name == "air"
 		and minetest.get_item_group(lnode.name, "wet") > 0
 end
 
 -- is_mowable_place reports whether maidroid can mow.
 local function is_mowable_place(pos)
 	local node = minetest.get_node(pos)
-	for _, target in ipairs(target_plants) do
-		if node.name == target then
-			return true
-		end
-	end
-	return false
+	return maidroid_aux.table.find(target_plants, node.name)
 end
 
--- search surrounding searchs maidroid surrounding.
-local function search_surrounding(self, pred)
-	for x = -searching_range.x, searching_range.x do
-		for y = -searching_range.y, searching_range.y do
-			for z = -searching_range.z, searching_range.z do
-				local pos = {x = x, y = y, z = z}
-				if pred(self, pos) then
-					return pos
-				end
-			end
-		end
-	end
-	return nil
+-- does_move reports whether the maidroid move in 1 frame.
+local function does_move(self)
+	local pos = self.object:getpos()
+	return self.pre_position.x ~= pos.x or self.pre_position.z ~= pos.z
 end
 
-local function on_start(self)
+local function change_direction_randomly(self)
+	local dir = {
+		x = math.random(0, 5) * 2 - 5, -- -5.0 ~ 5.0
+		y = 0,
+		z = math.random(0, 5) * 2 - 5, -- -5.0 ~ 5.0
+	}
+	local vel = vector.multiply(vector.normalize(dir), VELOCITY)
+	self.object:setvelocity(vel)
+	self:set_yaw_by_direction(vel)
+end
+
+local function start_walk_randomly(self)
 	self.state = state.WALK_RANDOMLY
-	self.object:setacceleration{x = 0, y = -10, z = 0}
-	self.object:setvelocity{x = 0, y = 0, z = 0}
+	self.destination = nil
+	self:set_animation(maidroid.animation_frames.WALK)
+	self.time_counter = 0
+	self:change_direction_randomly()
 end
 
-local function on_stop(self)
-	self.state = nil
-	self.object:setvelocity{x = 0, y = 0, z = 0}
-end
+do -- register farming core
 
-local on_resume = on_start
+	local function on_start(self)
+		self.object:setacceleration{x = 0, y = -10, z = 0}
+		self.object:setvelocity{x = 0, y = 0, z = 0}
+		self.state = state.WALK_RANDOMLY
+		self.pre_position = self.object:getpos()
+		self.time_counter = 0
+		self.destination = nil
+	end
 
-local on_pause = on_stop
+	local function on_stop(self)
+		self.object:setvelocity{x = 0, y = 0, z = 0}
+		self.state = nil
+		self.pre_position = nil
+		self.time_counter = nil
+		self.destination = nil
+	end
 
-local function on_step(self, dtime)
-	if self.state == state.WALK_RANDOMLY then
-		if self.time_counter >= SEARCHING_TIME_INTERVAL then
-			self.time_counter = 0 -- reset time_counter
+	local function on_step(self, dtime)
+		self:pickup_item() -- at first, pickup item dropped.
 
-			if self:has_seed_item() then
-				local d = search_surrounding(is_plantable_place)
-				if d ~= nil then
-					self.state = state.WALK_TO_PLANT
-					self.destination = d
+		if self.state == state.WALK_RANDOMLY then
+			if self.time_counter >= SEARCHING_TIME_INTERVAL then
+				self.time_counter = 0 -- reset time_counter
+				if self:has_seeditem() then
+					local dest = maidroid_core._aux.search_surrounding(is_plantable_place)
+					if dest ~= nil then
+						self.state = state.WALK_TO_PLANT
+						self.destination = dest
+						self.pre_position = self.object:getpos()
+						return
+					end
+				end
+
+				local dest = maidroid_core._aux.search_surrounding(is_mowable_place)
+				if dest ~= nil then
+					self.state = state.WALK_TO_MOW
+					self.destination = dest
+					self.pre_position = self.object:getpos()
 					return
 				end
-			end
-
-			local d = search_surrounding(is_mowable_place)
-			if d ~= nil then
-				self.state = state.WALK_TO_MOW
-				self.destination = d
+			else
+				if not self:does_move() then -- if doesn't move change direction.
+					self:change_direction_randomly()
+				end
+				self.time_counter = self.time_counter + 1
+				self.pre_position = self.object:getpos()
 				return
 			end
-		else
-			self.time_counter = self.time_counter + 1
-		end
-	elseif self.state == state.MOW then
 
-	elseif self.state == state.PLANT then
+		elseif self.state == state.MOW then
+			if self.time_counter >= MOWING_TIME_INTERVAL then
+				self.time_counter = 0
+				if is_mowable_place(self.destination) then
+					local node = minetest.get_node(self.destination)
+          local inv = self:get_inventory()
+          local stacks = minetest.get_node_drops(node.name)
 
-	elseif self.state == state.WALK_TO_MOW then
-		local pos = self.object:getpos()
-		if vector.distance(pos, self.destination) < TO_TARGET_DISTANCE then
-			local destination_node = minetest.get_node(self.destination)
-
-			if is_target_plant(destination_node.name) then
-				self.state = state.MOW
-			else
-				
-			end
-		elseif hoge then
-			
-		end
-	elseif self.state == state.WALK_TO_PLANT then
-		local pos = self.object:getpos()
-		if vector.distance(pos, self.destination) < TO_TARGET_DISTANCE then
-			local destination_node = minetest.get_node(self.destiantion)
-
-			if is_plantable_place(self.destination) then
+					minetest.remove_node(self.destination)
+          for _, stack in ipairs(stacks) do
+            local leftover = inv:add_item("main", stack)
+            minetest.add_item(self.destination, leftover)
+          end
+				end
+				self:start_walk_randomly()
+				self.pre_position = self.object:getpos()
+				return
 
 			else
-				
+				self.time_counter = self.time_counter + 1
+				self.pre_position = self.object:getpos()
+				return
+			end
+
+		elseif self.state == state.PLANT then
+			if self.time_counter >= PLANTING_TIME_INTERVAL then
+				self.time_counter = 0
+				if is_plantable_place(self.destination) then
+					local inv = self:get_inventory()
+					local stack = inv:get_stack("wield_item", 1)
+					local itemname = stack:get_name()
+					minetest.add_node(self.destination, {name = item_name, param2 = 1})
+          stack:take_item(1)
+          inv:set_stack("wield_item", 1, stack)
+				end
+				self:start_walk_randomly()
+				self.pre_position = self.object:getpos()
+
+			else
+				self.time_counter = self.time_counter + 1
+				self.pre_position = self.object:getpos()
+				return
+			end
+
+		elseif self.state == state.WALK_TO_MOW then
+			local pos = self.object:getpos()
+			if vector.distance(pos, self.destination) < TO_TARGET_DISTANCE then
+				local destination_node = minetest.get_node(self.destination)
+
+				if is_target_plant(destination_node.name) then
+					self.state = state.MOW
+					self:set_animation(maidroid.animation_frames.MINE)
+					self.object:setvelocity{x = 0, y = 0, z = 0}
+					self.pre_position = self.object:getpos()
+					return
+				else
+					self:start_walk_randomly()
+					self.preposition = self.object:getpos()
+					return
+				end
+
+			elseif not self:does_move() then
+				self:start_walk_randomly()
+				self.preposition = self.getpos()
+				return
+			end
+		elseif self.state == state.WALK_TO_PLANT then
+			local pos = self.object:getpos()
+			if vector.distance(pos, self.destination) < TO_TARGET_DISTANCE then
+				local destination_node = minetest.get_node(self.destiantion)
+
+				if is_plantable_place(self.destination) then
+					self.state = state.PLANT
+					self:set_animation(maidroid.animation_frames.MINE)
+					self.object:setvelocity{x = 0, y = 0, z = 0}
+					self.pre_position = self.object:getpos()
+				else
+					self:start_walk_randomly()
+					self.preposition = self.object:getpos()
+					return
+					
+				end
+			elseif hoge then
 			end
-		elseif hoge then
 		end
 	end
-end
 
-maidroid.register_core("maidroid_core:farming", {
-	description      = "maidroid core : farming",
-	inventory_image  = "maidroid_core_farming.png",
-	on_start         = on_start,
-	on_stop          = on_stop,
-	on_resume        = on_resume,
-	on_pause         = on_pause,
-	on_step          = on_step,
-})
+	maidroid.register_core("maidroid_core:farming", {
+		description      = "maidroid core : farming",
+		inventory_image  = "maidroid_core_farming.png",
+		on_start         = on_start,
+		on_stop          = on_stop,
+		on_resume        = on_start,
+		on_pause         = on_stop,
+		on_step          = on_step,
+	})
+
+end -- register farming core