Compressor containing a pressure regulating system (8) comprising an inlet valve (9); a piston (23) in a cylinder (24) connected thereto; a bridge (14) of this inlet valve (9) with a non-return valve (16) in it, characterized in that the piston (32) is a double-acting piston; the cylinder (24) on the side of the piston (23) turned away from the inlet valve is connected to a part (13) of the rotor chamber (2) situated near the inlet valve (9) via a pipe (28); and the cylinder (26) on the other side of the piston (23) is connected to the above-mentioned part (13) of the rotor chamber (2) and the non-return valve (16) via a pipe (29).