PURPOSE: To make it possible to release the internal pressure outside automatically when the internal pressure in the endoscope is higher than the air pressure.

CONSTITUTION: The endoscope is provided with an insertion part 4 with a means to image the area to be observed equipped, a holding part 6 connected to such insertion part, a universal code 7 with its one end connected to such holding part, a connector 8 connected to the other end of such universal code and a check valve, where normally the inside thereof is structured airtight and the check valve opens and cause the internal pressure to be released outside when such pressure within the endoscope is higher than the air pressure.