A pneumatically operated power tool includes an outer frame, a driving components, a pressure reduction valve, and a switching valve. The outer frame has a compressed air intake portion and defines therein a compressed air chamber. The driving components are disposed in the outer frame and are driven by a compressed air in the compressed air chamber. The pressure reduction valve defines a pressure receiving space and allows a compressed air to flow from the air intake portion to the compressed air chamber and to the pressure receiving space. The switching valve is movable between a first position where the compressed air flows from the compressed air intake portion to the pressure receiving space, and a second position where a communication between the compressed air intake portion and the pressure receiving space is blocked. The pressure reduction valve is configured to set a compressed air pressure in the compressed air chamber to a first pressure level if the switching valve is located at the first position and to set the compressed air pressure to a second pressure level lower than the first pressure level if the switching valve is located at the second position.