An air conditioner for vehicle mounted on a vehicle which is capable of traveling by an engine and has an engine automatic start and stop function capable of automatically starting and stopping the engine, the air conditioner for vehicle comprising: a refrigerating cycle which is constituted by suitably joining a compressor which is driven using the engine as a drive source and compresses a refrigerant, a condenser which condenses the compressed refrigerant, a decompression and expansion device which decompresses and expands the condensed refrigerant, and an evaporator which evaporates the decompressed and expanded refrigerant and has a cool storage function by piping; an evaporator temperature detection means which detects a temperature of the evaporator; and a control means which controls an operation state of the compressor, wherein the control means is capable of controlling the temperature of the evaporator by controlling the operation state of the compressor, the control means, when the control means determines that the temperature of the evaporator is to be controlled in an ordinary mode, controls the operation state of the compressor such that the temperature of the evaporator detected by the evaporator temperature detection means approaches a target temperature of the evaporator introduced from an ordinary mode target temperature map, and the control means, when the control means determines that the temperature of the evaporator is to be controlled in a cool storage mode, controls the operation state of the compressor such that the temperature of the evaporator detected by the evaporator temperature detection means approaches a target temperature of the evaporator introduced from a cool storage mode target temperature map, characterised in that the target temperature defined by the cool storage mode target temperature map and the ordinary mode target temperature map is based on the outside air temperature. a refrigerating cycle which is constituted by suitably joining a compressor which is driven using the engine as a drive source and compresses a refrigerant, a condenser which condenses the compressed refrigerant, a decompression and expansion device which decompresses and expands the condensed refrigerant, and an evaporator which evaporates the decompressed and expanded refrigerant and has a cool storage function by piping; an evaporator temperature detection means which detects a temperature of the evaporator; and a control means which controls an operation state of the compressor, wherein the control means is capable of controlling the temperature of the evaporator by controlling the operation state of the compressor, the control means, when the control means determines that the temperature of the evaporator is to be controlled in an ordinary mode, controls the operation state of the compressor such that the temperature of the evaporator detected by the evaporator temperature detection means approaches a target temperature of the evaporator introduced from an ordinary mode target temperature map, and the control means, when the control means determines that the temperature of the evaporator is to be controlled in a cool storage mode, controls the operation state of the compressor such that the temperature of the evaporator detected by the evaporator temperature detection means approaches a target temperature of the evaporator introduced from a cool storage mode target temperature map, characterised in that the target temperature defined by the cool storage mode target temperature map and the ordinary mode target temperature map is based on the outside air temperature.