Provided a reflecting device in which a mirror area is large, wide angle scanning is possible, and a size thereof is reduced, and particularly a downsized reflecting device that has a suitable specification as vehicle-mounted LiDAR. The reflecting device (1) includes an oscillation part (40), and the oscillation part (40) includes a mirror part (10) supported on a support frame (20), and a hinge part (30) engaging the mirror part (10) and the support frame (20). The mirror part (10) oscillates with respect to the support frame (20), and the hinge part (30) has a tensile strength of 1500 MPa or higher. A mass M of the mirror part (10) and a resonance frequency f 0 of the oscillation part (40) satisfy a relational expression (1) below, 0.49 * f 0 + 6.23 ≤ M ≤ 68.6 * f 0 + 46.8