An endoscope includes: a connector portion for electrically coupling to an external connector. The connector portion includes: a base portion having a tubular shape； and a tubular sleeve portion extending from the base portion, at least a part of an end portion of the sleeve portion being provided with a cutout portion. When a water-resistant cap is installed at the connector portion, the endoscope takes any state of a first state where an abutting portion of the water-resistant cap configured to abut on the sleeve portion abuts on the sleeve portion on a side of the base portion with respect to the cutout portion to hold an airtightness between the water-resistant cap and the connector portion, and a second state where the abutting portion abuts on or faces the sleeve portion including the cutout portion to make non-airtight between the water-resistant cap and the connector portion.
