A heat pump comprising: a main circuit which comprises a rotary compression device having a plurality of compression chambers and a condenser for condensing refrigerant passed through the rotary compression device and a first expansion device for expanding refrigerant passed through the condenser and a second expansion device for expanding refrigerant passed through the first expansion device and an evaporator for evaporating refrigerant expanded by the second expansion device; a first refrigerant injection flow path which is bypassed at the space between the condenser and the evaporator and injects refrigerant to one of the plurality of compression chambers; and a second refrigerant injection flow path which is bypassed at the space between the condenser and the evaporator and injects refrigerant to the other of the plurality of compression chambers; characterised in that the first refrigerant injection flow path comprises a first heat exchanger which exchanges heat of the refrigerant flowing from the first expansion device to the evaporator for heat of the refrigerant bypassed from the first expansion device to the first refrigerant injection flow path, and a first refrigerant control valve which throttles the refrigerant passing through the first refrigerant injection flow path; and the second refrigerant injection flow path comprises a second heat exchanger which exchanges heat of the refrigerant flowing from the first expansion device to the evaporator for heat of the refrigerant bypassed from the first expansion device to the second refrigerant injection flow path, and a second refrigerant control valve which throttles the refrigerant passing through the second refrigerant injection flow path; and the main circuit further comprises a refrigerant circulation flow path connecting the first expansion valve and the second expansion valve and a third heat exchanger disposed at the refrigerant circulation flow path; and the first heat exchanger and the second heat exchanger and the third heat exchanger are respectively in the shape of a plate, disposed side by side, and formed to one unit. a main circuit which comprises a rotary compression device having a plurality of compression chambers and a condenser for condensing refrigerant passed through the rotary compression device and a first expansion device for expanding refrigerant passed through the condenser and a second expansion device for expanding refrigerant passed through the first expansion device and an evaporator for evaporating refrigerant expanded by the second expansion device; a first refrigerant injection flow path which is bypassed at the space between the condenser and the evaporator and injects refrigerant to one of the plurality of compression chambers; and a second refrigerant injection flow path which is bypassed at the space between the condenser and the evaporator and injects refrigerant to the other of the plurality of compression chambers; characterised in that the first refrigerant injection flow path comprises a first heat exchanger which exchanges heat of the refrigerant flowing from the first expansion device to the evaporator for heat of the refrigerant bypassed from the first expansion device to the first refrigerant injection flow path, and a first refrigerant control valve which throttles the refrigerant passing through the first refrigerant injection flow path; and the second refrigerant injection flow path comprises a second heat exchanger which exchanges heat of the refrigerant flowing from the first expansion device to the evaporator for heat of the refrigerant bypassed from the first expansion device to the second refrigerant injection flow path, and a second refrigerant control valve which throttles the refrigerant passing through the second refrigerant injection flow path; and the main circuit further comprises a refrigerant circulation flow path connecting the first expansion valve and the second expansion valve and a third heat exchanger disposed at the refrigerant circulation flow path; and the first heat exchanger and the second heat exchanger and the third heat exchanger are respectively in the shape of a plate, disposed side by side, and formed to one unit.