The lens barrel, the image acquisition unit and their assembly method

Even small diameter lens barrel in long, easily and precisely assembled while filling the adhesive in place to secure airtightness, watertightness. The lens barrel (1) is provided with a lens (10) and the lens frame (2). Lens frame has a cylindrical body part (20), and an adhesive fixed lens pedestal component to the distal end opening of the cylindrical body part (30). Lens pedestal component has an opening (31a) to expose the distal end side optical surface of the lens, the tip base portion having an inner surface for supporting the lens (31b) around the opening (31), the distal end base portion round-shaped or arc-shaped side wall section erected on and a (32). Inner surface of the side wall portion (32a) is formed along the outer circumferential surface of the lens (14) is adhered to the outer peripheral surface. Upper surface of the side wall portion (32e) is in contact with the member (41) such as imaging the fiber determines the axial position of the member. Is disposed lenses to unevenly distributed position from the tubular body part of the member (41) is the central axis of the insertion portion to be inserted (AX), positioning surface on the opposite side of the side where the lens is unevenly distributed is unevenly distributed.