PROBLEM TO BE SOLVED: To provide a mouthpiece for endoscopic examination capable of preventing gas such as the air from being leaked from the mouth during an examination, and to provide a degassing prevention valve device used for the mouthpiece for an endoscope.SOLUTION: The mouthpiece for endoscopic examination 100 comprises: a mouthpiece body 11 with an insertion hole 12 for inserting an endoscope therethrough so as to be freely inserted and removed and a degassing prevention valve device 18 for applying airtight shielding in between the endoscope and the mouthpiece body 11.COPYRIGHT: (C)2016,JPO&INPIT【課題】検査中に口から空気などガスが漏れることを防止可能な内視鏡検査用マウスピース、および内視鏡用マウスピースに用いられる脱気防止弁装置を提供する。【解決手段】内視鏡を挿入抜去自在に挿通する挿通孔12を有するマウスピース本体11と、挿通孔12に挿通された上記内視鏡とマウスピース本体11との間を気密に封止する脱気防止弁装置18と、を設けて内視鏡検査用マウスピース100を構成する。【選択図】図1