Provided is an attachment for an endoscope (40), the attachment being attached to a leading end part of the endoscope having a leading end surface on which an observation window (46) for observing an inside of a subjects body and a first opening (50) for jetting a constant-pressure supplied gas are formed, the attachment including: a second opening (66, 76) provided at a position separate from the leading end surface a pipe conduit (62, 72) that communicates the first opening and the second opening with each other so as to jet the constant-pressure supplied gas from the second opening and a region separating member (60, 70) that separates a jetting region of the constant-pressure supplied gas jetted from the second opening from a region of view of the observation window. Accordingly, it is possible to prevent generated bubbles from blocking the field of view of an observation window when a constant-pressure gas is supplied via an opening of a treatment tool channel formed on a leading end surface of a flexible endoscope, to thereby secure the field of view.
