A traveling motor (19) of a reduction device (16) is mounted on a reduction gear (17) in a state protruding to an inner side in a left-and-right direction from a left side frame (7) and a right side frame (14) toward a center frame (6). Moreover, a motor guard (22) provided on a rear side which is the other side in a front-and-rear direction of each of the side frames (7) and (14), respectively, and covering the traveling motor (19) is constituted by an inner guard member (23) covering the traveling motor (19) and an outer guard member (25) covering the inner guard member (23) from an outer side.