A rotary cylinder type compressor includes: a cylinder that is rotatably placed in an inside of a housing; a rotor that is placed in an inside of the cylinder and is rotatable about an eccentric axis that is eccentric to a rotational central axis of the cylinder; and a partition member that partitions a working chamber formed between an outer peripheral surface of the rotor and an inner peripheral surface of the cylinder into a suction space and a compression space. When a pressure of fluid in the compression space is equal to or larger than a reference pressure, a contact stress, which is exerted at an adjoining portion between the outer peripheral surface of the rotor and the inner peripheral surface of the cylinder, is increased in comparison to a case where the pressure of the fluid in the compression space is smaller than the reference pressure.