A gate-shaped muffler mount including front and rear leg portions and a muffler attaching portion is attached to a mounting bracket for supporting an engine with bolts so as to straddle a hydraulic pump. One of mounting holes has a diameter larger than the diameter of the bolt, and the muffler mount is therefore rotatable around the other bolt along the axial direction of a bellows. By this rotation, the bellows can be positionally adjusted in the axial direction relative to an engine exhaust pipe so that assembly errors can be absorbed.