In a hydraulic excavator, in a rear part of an upper rotating body mounted on a lower traveling body is disposed an engine room, and in a front surface of a partition wall for partitioning the front surface side of the engine room from the exterior is provided a step serving as a foothold for opening and closing a bonnet and performing maintenance work. On the lower side of the step, a duct for exhausting the air within the engine room to the exterior is formed in a state that the step serves as an upper surface wall of the duct.