<p>Rigidity of a frame of a working vehicle is improved by a simple structure and production costs are reduced by reducing the number of parts of a working vehicle. Pipes (66) are provided on both left and right sides at the center in the front-rear direction of a side frame (62), and each pipe (66) has a rectangular cross-section and penetrates an intermediate partition in the front-rear direction from a mast section (64) up to a transmission section. Tie-down holes are formed in a front face plate (61) to which the front end of a frame (9) is connected, and a plate (64b) connected to a side frame (62) is provided at the bottom surface of each mast section (64) protruding outward from the side frame (62). Tanks installed on the working vehicle are suspended from the plate bodies (64b), and a lift arm installation boss provided at each mast section (64) is supported at both ends. A U-shaped reinforcement member (81) connects the upper surface of mast partition plate of a mast section (64) and left and right bosses.</p>
