An endoscope includes: a distal end opening of a treatment instrument insertion channel opened at a side surface of a distal end portion a treatment instrument elevator base that is provided at a position facing the distal end opening in the treatment instrument insertion channel and leads a distal end of a treatment instrument protruding from the distal end opening, to a desired position a first wall portion along the insertion direction of the distal end opening and a second wall portion at a proximal end side of the insertion direction of the distal end opening and provided with a groove in which a part of the treatment instrument elevator base is fitted when the treatment instrument elevator base is raised, and as the treatment instrument elevator base is raised, a guide wire protruding from the distal end opening is releasably engaged by contacting the treatment instrument elevator base, the first wall portion, and a surface constituting the groove of the second wall portion.
