PURPOSE: To reduce the size of a press device and to perform always stable press work by executing the press work in an air press by falling gravity of a weight.

CONSTITUTION: Pressurizing air is fed through an air hose 12 then through an air check valve 8 and the air is fed to an air hose 10 by the operation of a solenoid valve 7 to actuate an air cylinder 5 which moves a spindle 3 mounted with a working tool 13 together with a weight 4. After the work is placed on a receiving base 14, the valve 7 is operated to feed the pressurizing air through an air hose 9 to the cylinder 5, then the cylinder shaft moves downward and the weight 4 and the spindle 3 fall. The parts to be worked is worked with the tool 13 by the falling force thereof. With this device, the cylinder 5 may be of a small size to the extent of pulling up the weight 4 and the stable pressing work is accomplished irrespectively of the fluctuations in the air pressure.