A lens mount (101; 501; 1101; 1501) configured to be detachably mountable to a camera mount (201; 401; 1201; 1401) having a restricting portion and a plurality of first bayonet claw portions , the lens mount (101; 501; 1101; 1501) comprising: a plurality of second bayonet claw portions configured to enable engagement with the plurality of first bayonet claw portions , and a restricted portion configured to be restricted by the restricting portion when the lens mount (101; 501; 1101; 1501) is mounted to the camera mount (201; 401; 1201; 1401), wherein the plurality of second bayonet claw portions includes first and second adjacent bayonet claw portions adjacent to the restricted portion in a circumferential direction, and an opposite side bayonet claw portion disposed on an opposite side of the restricted portion with respect to the first and second adjacent bayonet claw portions in the circumferential direction, characterized in that 60° ≤ θ10 ≤ 100°, 60° ≤ θ20 ≤ 100°, 60° ≤ θ30 ≤ 100° and 60° ≤ θL ≤ 100° is satisfied, where, among internal angles of a quadrangle formed by connecting a center (107a3) of the opposite side bayonet claw portion , a center (107b3) of the second adjacent bayonet claw portion , a center (107c3) of the first adjacent bayonet claw portion , and a center of the restricted portion , θ10 is a first internal angle in which a vertex thereof is the center (107a3) of the opposite side bayonet claw portion , θ20 is a second internal angle in which a vertex thereof is the center (107b3) of the second adjacent bayonet claw portion , θ30 is a third internal angle in which a vertex thereof is the center (107c3) of the first adjacent bayonet claw portion , and θL is a fourth internal angle in which a vertex thereof is the center of the restricted portion . a plurality of second bayonet claw portions configured to enable engagement with the plurality of first bayonet claw portions , and a restricted portion configured to be restricted by the restricting portion when the lens mount (101; 501; 1101; 1501) is mounted to the camera mount (201; 401; 1201; 1401), wherein the plurality of second bayonet claw portions includes first and second adjacent bayonet claw portions adjacent to the restricted portion in a circumferential direction, and an opposite side bayonet claw portion disposed on an opposite side of the restricted portion with respect to the first and second adjacent bayonet claw portions in the circumferential direction, characterized in that 60° ≤ θ10 ≤ 100°, 60° ≤ θ20 ≤ 100°, 60° ≤ θ30 ≤ 100° and 60° ≤ θL ≤ 100° is satisfied, where, among internal angles of a quadrangle formed by connecting a center (107a3) of the opposite side bayonet claw portion , a center (107b3) of the second adjacent bayonet claw portion , a center (107c3) of the first adjacent bayonet claw portion , and a center of the restricted portion , θ10 is a first internal angle in which a vertex thereof is the center (107a3) of the opposite side bayonet claw portion , θ20 is a second internal angle in which a vertex thereof is the center (107b3) of the second adjacent bayonet claw portion , θ30 is a third internal angle in which a vertex thereof is the center (107c3) of the first adjacent bayonet claw portion , and θL is a fourth internal angle in which a vertex thereof is the center of the restricted portion . <EOS>