To prevent warm air heated by an engine from being moved to a suction side of a radiator, so as to enhance the maintainability of the radiator.A work machine 1 includes a travelling machine body equipped with an engine, an openable and closable engine hood 11 covering the engine, a shroud 154 and a radiator 153 disposed at a side of one side portion of the engine in the engine hood 11, and shielding members 146, 147 filling a gap between the shroud 154 and the engine hood 11. The first shielding member 146 is disposed on a peripheral wall of the shroud 154 surrounding the outer circumference of the radiator 153, and includes a break portion above a water supply portion 142 of the radiator 153. The second shielding member 147 is disposed at the engine hood 11a so as to connect to the break portion of the first shielding member 146 when the engine hood 11a is closed.本發明之課題,在於一邊抑制因引擎之熱而升溫之暖空氣繞進散熱器之吸入側,一邊提高對散熱器之維護性。本發明之作業機1具備搭載有引擎之移行機體、覆蓋引擎之可開閉之引擎蓋11、在引擎蓋11內被配置於引擎之一側部側之擋板154及散熱器153、以及閉塞擋板154與引擎蓋11之間的間隙之遮蔽構件146、147。第1遮蔽構件146係安裝於包圍散熱器153之外周之擋板154之周壁部,並且於散熱器153之供水口部142之上方被阻斷。第2遮蔽構件147係以於引擎蓋11a為關閉狀態時連接於第1遮蔽構件146之阻斷部分的方式被安裝於引擎蓋11a。