To provide a revolving working machine capable of preventing the temperature of a battery from rising even if the battery is arranged in a place where temperature rises.

This revolving working machine is constituted by providing a revolving frame 15 provided on a traveling body 3 to revolve freely, arranging a radiator 43 on a side of an engine 42 mounted on the revolving frame 15, and providing a cooling fan 49 for taking outside air into a radiator room RR, letting the taken-in outside air pass through the radiator 43, and circulating it into an engine room ER between the radiator 43 and the engine 42. This revolving working machine also includes a battery room BR storing the battery 52 in a tank room TR storing a hydraulic fluid tank 45, an outside air introduction part 136 for taking outside air into the battery room BR, and a communicating part 134 for communicating the battery room BR and the radiator room RR mutually so that the air in the battery room BR is sucked by the cooling fac 49.