DRIVING MACHINE

A driving machine capable of performing replenishment of air in a pneumatic chamber includes: a housing; a cylinder provided within the housing; a pneumatic chamber spatially connected to the cylinder; a piston reciprocally movably provided in the cylinder; a blade attached to the piston and striking a stopper; and a moving mechanism reducing an internal volume of either the pneumatic chamber or the cylinder by a motor, and the driving machine drives the stopper by repulsive force of compressed air. The driving machine has a pressure accumulating mode in which the pneumatic chamber is pressurized by the motor from a state where the pneumatic chamber communicates with outside, and a striking mode in which the piston is moved by the motor from a bottom dead point to a top dead point in the cylinder and then from the top dead point toward the bottom dead point, thereby driving the stopper.