Endoscope and endoscope system

An endo scope having an insertion portion to be inserted into an object to be observed, comprising:

• a tubular holder member mounted to the insertion portion and having an open front end portion including a shoulder surface surrounded by an axial wall;
• a lens barrel received in the holder member;
• an objective lens system having an optical axis and held by the lens barrel;
• and
• a light-transmissive closure member fitted into a front opening defined by the axial wall of the holder member and the shoulder surface, and fixed to the front opening by a bonding agent interposed between an outer circumferential surface of the closure member and an opposing inner circumferential surface of the open front end portion of the holder member, wherein
• the shoulder surface extends from the axial wall in a direction perpendicular to the optical axis,
• a space axially adjoining the shoulder surface in a direction along the optical axis is defined between an outer circumferential surface of a front end portion of the lens barrel and an opposing inner circumferential surface of the holder member,
• the space is provided radially inward of the shoulder surface, and
• the closure member fitted into the front opening is fixed to the shoulder surface.