An endoscope includes: an insertion portion that includes a distal end portion in which an image sensor and a laser diode are disposed, a bending portion, and a flexible portion, the image sensor outputting an image pickup signal, the laser diode converting the image pickup signal into an optical signal; an operation portion; an universal cord; a connector; an optical fiber that is inserted through the insertion portion and transmits the optical signal; and a stress relief portion that changes an effective length L1 of the optical fiber in accordance with a stress applied to the optical fiber, the effective length being a length of the optical fiber along an insertion direction thereof.