A control valve (1, 201, 301, 401) for a variable displacement compressor for varying a discharging capacity of the compressor for compressing refrigerant led into a suction chamber and discharging the compressed refrigerant from a discharge chamber, by regulating a flow rate or pressure of at least one of the refrigerant led into a crankcase from the discharge chamber and the refrigerant led out to the suction chamber from the crankcase, the control valve (1, 201, 301, 401) comprising: a body (5, 46, 56, 58, 205, 305, 405) having a main passage, which communicates between the discharge chamber and the crank case, and a sub-passage, which communicates between the crankcase and the suction chamber; a main valve seat provided in the main passage; a main valve element (30, 330, 430) configured to open and close a main valve by touching and leaving the main valve seat; a sub-valve seat provided in the sub-passage; a sub-valve element (36, 236, 336, 436) configured to open and close a sub-valve by touching and leaving the sub-valve seat; a pressure-sensing section configured to sense a predetermined pressure-to-be-sensed and configured to generate a drive force exerted in an opening direction of the main valve in accordance with a magnitude of the pressure-to-be-sensed; and a solenoid configured to generate a drive force in a closing direction of the main valve in accordance with an amount of current supplied; wherein the pressure-sensing section is provided on one side of the main valve element (30, 330, 430), and the solenoid is provided on the other side thereof, characterised in that the sub-valve seat is formed integrally with the body (5, 46, 56, 58, 205, 305, 405), and wherein a seal section diameter of the sub-valve element (36, 236, 336, 436) in the sub-valve is larger than a seal section diameter of the main valve element (30, 330, 430) in the main valve. a body (5, 46, 56, 58, 205, 305, 405) having a main passage, which communicates between the discharge chamber and the crank case, and a sub-passage, which communicates between the crankcase and the suction chamber; a main valve seat provided in the main passage; a main valve element (30, 330, 430) configured to open and close a main valve by touching and leaving the main valve seat; a sub-valve seat provided in the sub-passage; a sub-valve element (36, 236, 336, 436) configured to open and close a sub-valve by touching and leaving the sub-valve seat; a pressure-sensing section configured to sense a predetermined pressure-to-be-sensed and configured to generate a drive force exerted in an opening direction of the main valve in accordance with a magnitude of the pressure-to-be-sensed; and a solenoid configured to generate a drive force in a closing direction of the main valve in accordance with an amount of current supplied; wherein the pressure-sensing section is provided on one side of the main valve element (30, 330, 430), and the solenoid is provided on the other side thereof, characterised in that the sub-valve seat is formed integrally with the body (5, 46, 56, 58, 205, 305, 405), and wherein a seal section diameter of the sub-valve element (36, 236, 336, 436) in the sub-valve is larger than a seal section diameter of the main valve element (30, 330, 430) in the main valve.