(Amended) A scroll compressor, comprising: a casing having a hermetic inner space divided into a low pressure portion and a high pressure portion; a high/low pressure dividing plate dividing the inner space of the casing into the low pressure portion and the high pressure portion; an orbiting scroll disposed within the inner space of the casing and performing an orbiting motion; a non-orbiting scroll forming a compression chamber together with the orbiting scroll, the compression chamber having a suction chamber, an intermediate pressure chamber and a discharge chamber; a back pressure chamber assembly coupled to the non-orbiting scroll to form a back pressure chamber; a plurality of valve accommodation grooves (161a, 151c) provided on at least one of the non-orbiting scroll or the back pressure chamber assembly; a plurality of bypass holes formed from the intermediate pressure chamber into the plurality of valve accommodation grooves (161a, 151c) in a penetrating manner, respectively; a communication passage (161b, 151d) provided between the plurality of valve accommodation grooves (161a, 151c) to communicate the plurality of valve accommodation grooves with each other; a discharge hole (161c, 151e) provided between a passage and the low pressure portion to communicate the passage and the low pressure portion, wherein the passage includes the plurality of valve accommodation grooves (161a, 151c) and the communication passage (161b, 151d); a plurality of check valves respectively accommodated in the plurality of valve accommodation grooves (161a, 151c) to open and close the bypass holes according to pressure of the intermediate pressure chamber, a control valve disposed outside the non-orbiting scroll to open and close the discharge hole (161c, 151e) and to control a capacity of the compressor, characterized by a back pressure plate forming a part of the back pressure chamber assembly and fixed to a top of a disk portion of the non-orbiting scroll, wherein the communication passage is a communication groove, and wherein the plurality of valve accommodation grooves (161a, 151c) and the communication groove (161b, 151d) are formed on a rear surface of the disk portion of the non-orbiting scroll in contact with a lower surface of the back pressure plate, or on the lower surface of the back pressure plate in contact with the rear surface of the disk portion of the non-orbiting scroll. a casing having a hermetic inner space divided into a low pressure portion and a high pressure portion; a high/low pressure dividing plate dividing the inner space of the casing into the low pressure portion and the high pressure portion; an orbiting scroll disposed within the inner space of the casing and performing an orbiting motion; a non-orbiting scroll forming a compression chamber together with the orbiting scroll, the compression chamber having a suction chamber, an intermediate pressure chamber and a discharge chamber; a back pressure chamber assembly coupled to the non-orbiting scroll to form a back pressure chamber; a plurality of valve accommodation grooves (161a, 151c) provided on at least one of the non-orbiting scroll or the back pressure chamber assembly; a plurality of bypass holes formed from the intermediate pressure chamber into the plurality of valve accommodation grooves (161a, 151c) in a penetrating manner, respectively; a communication passage (161b, 151d) provided between the plurality of valve accommodation grooves (161a, 151c) to communicate the plurality of valve accommodation grooves with each other; a discharge hole (161c, 151e) provided between a passage and the low pressure portion to communicate the passage and the low pressure portion, wherein the passage includes the plurality of valve accommodation grooves (161a, 151c) and the communication passage (161b, 151d); a plurality of check valves respectively accommodated in the plurality of valve accommodation grooves (161a, 151c) to open and close the bypass holes according to pressure of the intermediate pressure chamber, a control valve disposed outside the non-orbiting scroll to open and close the discharge hole (161c, 151e) and to control a capacity of the compressor, characterized by a back pressure plate forming a part of the back pressure chamber assembly and fixed to a top of a disk portion of the non-orbiting scroll, wherein the communication passage is a communication groove, and wherein the plurality of valve accommodation grooves (161a, 151c) and the communication groove (161b, 151d) are formed on a rear surface of the disk portion of the non-orbiting scroll in contact with a lower surface of the back pressure plate, or on the lower surface of the back pressure plate in contact with the rear surface of the disk portion of the non-orbiting scroll.