Abstract: A pressure receiving member which has a diaphragm held in a pressure receiving case is manufactured independently of a main sensor body member, which has a switch accommodated in a switch case. The pressure receiving member and the main sensor body member are then assembled to provide a pressure sensor. According to the present invention, since the pressure receiving portion and the main sensor body are manufactured individually, a diaphragm movement test can be carried out individually of the testing of switch turning on and off, and hence only a satisfactory pressure receiving portion and a main sensor body which passed the respective tests will be utilized in the operation of assembling pressure sensors.