104 and whose pulsating noise has been attenuated by means of the discharge mufflers 124 and 125 as described hereinbefore contains still a large quantity of oil droplets thus the refrigerant is moved upward through an air gap 129 in the motor and a gap 130 formed between the motor 103 and the casing 101 to separate the oil mist which is then returned to an oil sump 131 in the casing the refrigerant is then supplied through the discharge pipe 107 to an outside refrigerant cycle system not shown as pressurized gas in this process if a separate adiabatic pipe 133 is inserted in a passage 132 which connects the suction pipe 106 to the cylinder 113 to prevent refrigerant flowing into the cylinder 113 from overheating in the process of compressing the sucked refrigerant then the comoress ion efficiency of the compressing device 104 will be improved and the compressor will be well suited especially to low temperature refrigerant compressors such as a refrigerator further if the discharge muffler 124 is made of a cup which is fabricated by forging and if the cup is securely fixed to the cylinder 113 with a bolt not shown then the compressor will produce less noise as compared with a compressor equipped with a muffler which is fabricated from a sheet metal by forming since the rotary compressor 100c is provided with the discharge port 122 and discharge valve 123 for discharging the refrigerant pressurized in the cylinder 113 first toward the motor 103 as well as the discharge muffler 124 fully utilizing the space.