To provide a helical-shaped liquid-ring type compressor that can certainly eliminate shortage of sealing liquid in a suction portion, and has a sealing liquid supply mechanism requiring no large scale supply mechanism for the sealing liquid.

This compressor has a suction port 5 of actuation medium gas, a delivery port 7 of the actuation medium gas, a sealing liquid suction opening 6 positioned on the suction port 5 side, and a sealing liquid return opening 8 positioned on the delivery port side, and is provided with an inner casing 2 capable of sealing a sealing liquid 13, an outer casing 4 accommodating the inner casing, an impeller 3 reflectively arranged in the inner casing 2. In the impeller 3, one or several streaks of helical blades 12 are mounted to a rotor shaft, and a clearance 14 between the inner casing 2 and the outer casing 4 defines a sealing liquid passage from the sealing liquid return opening 8 to the sealing liquid suction opening 6.