An air conditioner comprising: a compressor configured to compress refrigerant, a rotation number of the compressor being variably controllable; a condenser configured to condense the refrigerant compressed by the compressor; an expansion valve configured to decompress the refrigerant condensed by the condenser; an evaporator configured to evaporate the refrigerant decompressed by the expansion valve; and a temperature detection unit attached to the condenser and configured to detect a temperature of the refrigerant in the condenser, the expansion valve being configured to be capable of adjusting a flow rate per unit time of the refrigerant flowing through the expansion valve by adjusting a degree of opening of the expansion valve, the expansion valve being a temperature-type expansion valve, the temperature detection unit being a temperature sensitive cylinder, and the degree of opening of the expansion valve being increased when the temperature of the refrigerant detected by the temperature detection unit rises, and the degree of opening of the expansion valve being decreased when the temperature of the refrigerant detected by the temperature detection unit falls; wherein the expansion valve has a case, a diaphragm, a valve body connected to the diaphragm and a valve seat attached inside case, the case has a first chamber and a second chamber partitioned by the diaphragm, the first chamber is configured such that the refrigerant enclosed in temperature detection unit flows into and out the first chamber, the second chamber houses the valve body and the valve seat and is configured such that the refrigerant condensed by the condenser flows into the second chamber, the diaphragm is configured such that the diaphragm is deformed by the differential pressure between a pressure of the first chamber which is an internal pressure of the temperature detection unit and a pressure of the second chamber which is a pressure of the refrigerant condensed by the condenser, the expansion valve is configured to be capable of adjusting a flow rate per unit time of the refrigerant flowing through the expansion valve by adjusting a degree of opening of the expansion valve by movement of the valve body due to deformation of the diaphragm. a compressor configured to compress refrigerant, a rotation number of the compressor being variably controllable; a condenser configured to condense the refrigerant compressed by the compressor; an expansion valve configured to decompress the refrigerant condensed by the condenser; an evaporator configured to evaporate the refrigerant decompressed by the expansion valve; and a temperature detection unit attached to the condenser and configured to detect a temperature of the refrigerant in the condenser, the expansion valve being configured to be capable of adjusting a flow rate per unit time of the refrigerant flowing through the expansion valve by adjusting a degree of opening of the expansion valve, the expansion valve being a temperature-type expansion valve, the temperature detection unit being a temperature sensitive cylinder, and the degree of opening of the expansion valve being increased when the temperature of the refrigerant detected by the temperature detection unit rises, and the degree of opening of the expansion valve being decreased when the temperature of the refrigerant detected by the temperature detection unit falls; wherein the expansion valve has a case, a diaphragm, a valve body connected to the diaphragm and a valve seat attached inside case, the case has a first chamber and a second chamber partitioned by the diaphragm, the first chamber is configured such that the refrigerant enclosed in temperature detection unit flows into and out the first chamber, the second chamber houses the valve body and the valve seat and is configured such that the refrigerant condensed by the condenser flows into the second chamber, the diaphragm is configured such that the diaphragm is deformed by the differential pressure between a pressure of the first chamber which is an internal pressure of the temperature detection unit and a pressure of the second chamber which is a pressure of the refrigerant condensed by the condenser, the expansion valve is configured to be capable of adjusting a flow rate per unit time of the refrigerant flowing through the expansion valve by adjusting a degree of opening of the expansion valve by movement of the valve body due to deformation of the diaphragm.