A working machine is constituted so as to mount a guard cover hinge, a radiator duct, a canopy right support, a hood catch and the right end part of a seat stand on a radiator support. The working machine further comprises a mounting column provided on the opposite side of the radiator support so as to mount a hood hinge, a left side panel, the left end part of the seat stand and a muffler cover thereon. According to such a structure, a mounting member shared by a plurality of constituting members can be used also as a positioning support between members, and the workability in assembling can be improved.