An electromagnetic control valve which is capable of controlling with small electromagnetic force is provided. In such electromagnetic control valve, a pressure-sensitivity control mechanism is provided in a space leading to the suction side of the compressor such that the pressure-sensitivity control mechanism faces to the crankcase pressure introducing opening of the valve main body. This pressure-sensitivity control mechanism is formed by a piston which comes into contact with the bottom surface of the valve rod. The differential pressure between the crankcase pressure and the suction pressure of the compressor is detected by the piston. Upon receipt of detection signals from a temperature sensor and a pressure sensor and an external signal, the pressure-sensitivity control mechanism adjusts the flow of refrigerant from the discharge side (high-pressure side) to the crankcase side of the compressor. Thus, the differential pressure can be controlled.