The door switch (1) includes an actuator (20) and a sensor (10). When a door is closed, a front surface (S1) of the sensor (10) and an opposite surface of the actuator (20) are in contact with each other, and separated when the door is open. The sensor (10) includes a light source part (150) for emitting detection light according to a reception state of a detection signal outputted from the actuator, a collector (122) for collecting the detection light, a diffuse light guide part (123) formed to be connected to the collector and for diffusing and emitting the detection light collected by the collector, and a back surface display part (121) formed on a back surface (B1) side of the sensor to be in contact with the diffuse light guide part and having a main surface (125) for emitting the detection light emitted from the diffuse light guide part.