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 includes an oscillation part, and the oscillation part includes a mirror part supported on a support frame, and a hinge part engaging the mirror part and the support frame. The mirror part oscillates with respect to the support frame, and the hinge part has a tensile strength of 1500 MPa or higher. A mass M of the mirror part and a resonance frequency f0 of the oscillation part satisfy a relational expression (1) below, 0.49*f0+6.23≤M≤68.6*f0+46.8   (1)