A rotary compressor comprising: a cylinder having an inner peripheral surface defined in an annular shape to define a compression space, and provided with a suction port configured to communicate with the compression space to suck refrigerant; a roller rotatably provided in the compression space of the cylinder, and provided with a plurality of vane slots providing a back pressure at one side thereinside and arranged at a predetermined interval along an outer peripheral surface; a plurality of vanes (1351 to 1353) slidably inserted into the vane slots to rotate together with the roller, front end surfaces of which come into contact with an inner periphery of the cylinder by the back pressure to partition the compression space into a plurality of compression chambers; and a main bearing and a sub bearing provided at both ends of the cylinder, respectively, and disposed to be spaced apart from each other to define both surfaces of the compression space, respectively, wherein when high-pressure refrigerant is accommodated in a space defined by boundaries comprising, at least, a front end surface of one of the plurality of vanes (1351 to 1353), a contact point between the roller and the cylinder, and an inner periphery of the cylinder, the back pressure is maintained at a predetermined level to allow the front end surface of the vane (1351 to 1353) to come into contact with the inner periphery of the cylinder until the high-pressure refrigerant is bypassed to the suction port, wherein at least one back pressure pocket concavely disposed to communicate with the compression space is provided on at least one of the main bearing and the sub bearing, wherein a back pressure chamber in which a rear end of the vane is accommodated is disposed at an inner end of the vane slot so as to receive a back pressure from the back pressure pocket while communicating with the back pressure pocket to pressurize the vane toward the inner periphery of the cylinder, and wherein the back pressure pocket communicates with the back pressure chamber to allow the front end surface of the vane to come into contact with the inner periphery of the cylinder until the high-pressure refrigerant is bypassed to the suction port, characterized in that when the center of the roller is defined as the origin, an angle between a contact point, on which an outer periphery of the roller and an inner periphery of the cylinder are in contact, and one side of the suction port is 38 to 40 degrees. a cylinder having an inner peripheral surface defined in an annular shape to define a compression space, and provided with a suction port configured to communicate with the compression space to suck refrigerant; a roller rotatably provided in the compression space of the cylinder, and provided with a plurality of vane slots providing a back pressure at one side thereinside and arranged at a predetermined interval along an outer peripheral surface; a plurality of vanes (1351 to 1353) slidably inserted into the vane slots to rotate together with the roller, front end surfaces of which come into contact with an inner periphery of the cylinder by the back pressure to partition the compression space into a plurality of compression chambers; and a main bearing and a sub bearing provided at both ends of the cylinder, respectively, and disposed to be spaced apart from each other to define both surfaces of the compression space, respectively, wherein when high-pressure refrigerant is accommodated in a space defined by boundaries comprising, at least, a front end surface of one of the plurality of vanes (1351 to 1353), a contact point between the roller and the cylinder, and an inner periphery of the cylinder, the back pressure is maintained at a predetermined level to allow the front end surface of the vane (1351 to 1353) to come into contact with the inner periphery of the cylinder until the high-pressure refrigerant is bypassed to the suction port, wherein at least one back pressure pocket concavely disposed to communicate with the compression space is provided on at least one of the main bearing and the sub bearing, wherein a back pressure chamber in which a rear end of the vane is accommodated is disposed at an inner end of the vane slot so as to receive a back pressure from the back pressure pocket while communicating with the back pressure pocket to pressurize the vane toward the inner periphery of the cylinder, and wherein the back pressure pocket communicates with the back pressure chamber to allow the front end surface of the vane to come into contact with the inner periphery of the cylinder until the high-pressure refrigerant is bypassed to the suction port, characterized in that when the center of the roller is defined as the origin, an angle between a contact point, on which an outer periphery of the roller and an inner periphery of the cylinder are in contact, and one side of the suction port is 38 to 40 degrees.