PURPOSE: To facilitate the mounting of a working tool in a proper manner by protruding a tool bar to the side from a support frame mounted on the upper part of a transmission case and having a handle pipe on the upper part thereof, and mounting the working tool on this tool bar.

CONSTITUTION: A support frame 2 is provided by means of locking members 20, 20, on the upper part of a transmission case 1 arranged along the front and rear direction at the center of a machine body, a handle frame 21 with left and right handle pipes 3, 3 is provided at the upper part of the support frame 2. In this case, the basic end of a tool bar is integrally mounted on the members 20, 20 through a basic plate 30. A working tool 7 provided with other members' storing part 6 through a fitting unit 32 is set so as to slide freely in the range of length of the bar 5. The tool 7 is fixed to be adjusted freely vertically at the vertical intermediate part, at the rear end of an arm 33 protrud ing rearwards from the fitting unit 32. It is thus possible to enable free and easy adjustment of the handle pipe 3 and the working tool 7.