An internal intermediate pressure type two-stage compression rotary compressor (10) is provided with an electrically driven element (14) disposed within a sealed vessel (12), and first and second rotary compression elements (32, 34) driven by the electrically driven element (14), and is structured such as to discharge CO2 refrigerant gas compressed at a first stage by the first rotary compression element (32) within the sealed vessel (12) and compress the discharged refrigerant gas having an intermediate pressure at a second stage by the second rotary compression element (34) via an accumulator (106). The rotary compression elements (32, 34) include upper and lower cylinders (38, 40), upper and lower rollers (46, 48) eccentrically rotating within the cylinder and upper and lower vanes (50, 52) brought into contact with the rollers so as to section the inner portions of the upper and lower cylinders into high pressure chambers and low pressure chambers. A ratio of volume between the upper and lower cylinders (38, 40) executing the compression operation at the first stage and the second stage is set to 1:0.65 so that an equilibrium pressure becomes equal to an intermediate pressure. Since a pressure change at a time of starting is reduced, an oil foaming is restricted and it, is possible to easily employ a withstand pressure design of a sealed vessel, it is possible to easily design a withstand pressure vessel and it is possible to reduce a weight of the pressure vessel.