To provide a rational rotary type compression mechanism to improve compression efficiency through simple constitution and a device for utilizing the compression mechanism.

A crescent-shaped gap chamber 311X formed by a circular outer surface 320A of a rotor 320 and a circular inner surface 311B of a cylinder 311 is partitioned into a suction chamber 311X1 and a pressure chamber 311B2 by a vane 325 making contact with a circular outer surface 320A by the elastic force of a spring 326. When a rotor 320 is rotated, a gap chamber 311X is rotated, fluid sucked and compressed through a suction hole 500 is discharged through a discharge opening 701. A groove part 500A or a groove part 500B extending along the direction of the height of the cylinder 311 is formed in the spot of the circular inner surface 311B of the suction hole 500A and suction resistance of fluid is decreased. A refrigerant compression device for a refrigerating device is used as the device for utilizing the compression mechanism.