To allow a driver to visually confirm while seated on a driver's seat and also to correctly and simply measure a load weight of a vehicle by calculating the load weight based on respective output signals from a clump cylinder sensor and a pressure sensor for displaying the weight.

A dump cylinder sensor 10 for measuring a load weight is provided between a dump box 2 which dumps up/down and a chassis 3, while a pressure sensor (load sensor) 20 is provided on a support shaft 4 of the clump box 2. A clump cylinder is actuated by hydraulic pressure by controlling a control part in a driver's cab 5, whereby the dump box 2 dumps up/down. A display 30 for displaying a weight value of the load mounted in the dump box 2 which has been calculated based on the dump cylinder sensor 10 and the pressure sensor 20 is provided in the driver's cab 5. The pressure sensor 20, the dump cylinder sensor 10, etc., can be added to an existing vehicle.