An interchangeable lens assembly (100) includes a plurality of lens-side claw portions (107a, 107b, 107c) configured to enable engagement with a plurality of camera-side claw portions, and a lock pin groove portion (102) in which a lock pin (203) is inserted. Furthermore, θ1 is an angle formed between a line passing a fifth lens-side end (107c1) and an optical axis 0, and a line passing a center of a lock pin groove portion and the optical axis O, and θ2 is an angle formed between a line passing a fourth lens-side end (107b2) and the optical axis O, and a line that passes the center of the lock pin groove portion and the optical axis O. In the above, θ1 and θ2 satisfy a predetermined conditional expression.