A proximity sensor apparatus has a detection electrode that forms an electrostatic capacitance between the detection electrode and an object to be detected. The detection electrode is fitted to an electrode base plate. The detection section detects electrostatic capacitance based on output of the detection electrode. The electrode base plate is supported by a push-button switch. When the object to be detected approaches the detection electrode, the electrostatic capacitance changes. Approach of the object to be detected can be detected by a change in electrostatic capacitance. When the object to be detected contacts the detection electrode, the push-button switch is turned on. The push-button switch is turned on, and thereby contact of the object to be detected can be detected.