Detection device.

The purpose of the present invention is to provide a detection device that detects the occurrence of an event (so-called "double capping") in which two caps are disposed on one container. To that end, the detection device (10,10A) of the present invention has two types of sensors provided on a production line (100) for a commercial product in which an opening (1A) of a container (1) is sealed with a cap (2), said sensors being a proximity sensor (3) along a path where the container (1) moves and a sensor (4: for example, a transmission sensor) equipped with a transmitter (4A), which is inside the same path, and a receiver (4B). An area detected by the sensors (3,4) is an area where the cap (2) is not present in a normal state (a state in which double capping has not occurred), but where a subsequent cap (2-1) is present if...