To prevent the generation of black smoke caused by incomplete combustion by increasing fuel injection in torque increase starting up, and suppressing excess fuel injection within a torque increase metering region.

This torque increase device is equipped with a case body 11 fixed to a governor wall 25; a torque pin 12 projecting from the case body 11 and facing so as to contact with a governor lever 1; a torque spring 13 energizing the torque pin 12 toward the pin projecting side; a pin meter 15 metering and regulating a coming in and out gap t of the torque pin 12; and a back spring 17 energizing the pin meter 15 toward the pin projecting side, and constituted so as to move back the torque pin 12 to the starting increase position St against the back spring 17. The torque spring 13 is composed of a main spring 13a for energizing to the pin projection side and a sub-spring 13b, and a spring constant in a torque increase first half region is set small and a spring constant in a torque increase latter half region is set relatively large.