PURPOSE: To enable safety in work operation and competent operation by recognizing working force and speed by the resisting force to the depression of a foot pedal.

CONSTITUTION: When the foot pedal 3 is depressed, the load on a ram 7 is detected with a pressure gage (detector) G and its information is fed to a variable valve (control section) 33. The working force and working speed of the ram 7 are controlled with the variable valve 33 by adjusting an opening degree in accordance with the sent information on the load to the ram 7. Then, the supply of air to an air cylinder (resistance imparting part) 35 is increased in accordance with the depression of a pedal board 21, the piston rod 41 of the air cylinder 35 is driven and a pinion gear (transmitting means) 47 is rotatively driven with the rack (transmitting means) 43 of this piston rod 41. Since a sectorial gear (transmitting means) 45 provided at the tip of the pedal board 21 is rotatively driven with this pinion gear 47, the pedal board 21 is rocked in the antidepressing direction. This rocking becomes the resisting force to the depression of the pedal board 21.