To provide a forcipate plug of an endoscope certainly preventing the leakage of a contaminated liquid caused by water hammering or the like in both states at the times of use and non-use of a treatment implement.

An inside closing film 17 consisting of a material having elasticity, which directly receives the pressure in the treatment implement inserting channel 3 formed in a forcipate plug main body 11, is formed into a V-shaped cross-sectional form gradually narrowed toward its depth and a slit 18, which is closed in a normal state but widened by the passage of the treatment implement 50 inserted into and pulled out of the treatment implement inserting channel 3, is formed at the tip part of the inside closing film 17. A circular small hole 16 widened by the passage of the treatment implement 50 inserted into and pulled out of the treatment implement inserting channel 3 is formed to an outside closing film 15 consisting of the material having elasticity formed in a lid member 12.