A second lens frame 10 has a shape including: a contact portion 11 having a cylindrical shape with a diameter smaller than an inner diameter of a space portion of a first lens frame 3, a distal end portion thereof being brought into contact with an end face 4a of the first lens frame 3； and a fitting portion 12 having a diameter larger than that of the contact portion 11 in a cylindrical shape fitting on an inner wall surface of the first lens frame 3, and when the second lens frame 10 is inserted into the space portion of the first lens frame 3, a gap 5 is formed between the second lens frame and the inner wall surface of the first lens 3. Accordingly, when the second lens frame 10 is inserted into the first lens frame 3 and fitted therein, a contact area between the first lens frame 3 and the second lens frame 10 becomes small, thereby reducing insertion resistance and capable of reliably bringing a distal end portion of the second lens frame 10 into contact with the end face 4a of a flange portion 4 of the first lens frame 3, and as a result, variations in position in an optical axis direction are eliminated, enabling provision of a stable optical precision.
