The purpose of the present invention is to provide a combine harvester with which it is possible to prevent a delay in the engaging of a side clutch (121) in a forward movement operation involving the returning of an operating lever (43), and with which it is possible to improve the rotational performance and the responsiveness of the side clutch (121) engaging operation. In this combine harvester, drive power is transmitted to left and right running crawlers (2) via left and right side clutches (121) that are provided in a transmission case (63) for driving the left and right running crawlers (2), left and right side clutch arms (136) for disengaging the left and right side clutches (121) are provided in the transmission case (63), and an operator switches between the left and right side clutch arms (136) by operating an operating lever (43) for performing a left/right tilting operation so that the left or right side clutch arm (136) is caused to rotate to the left or right. The present invention is provided with a side clutch hydraulic switching body (138) having left and right side clutch cylinders (137). The side clutch hydraulic switching body (138) is disposed on the outside of the transmission case (63) with a hydraulic switching bracket (139) interposed therebetween, and left and right tensioning springs (181) are connected to the left and right side clutch arms (136), respectively, said springs (181) being used to return said arms (136).