A mirror device includes a support portion, a movable portion, and a pair of torsion bars disposed on both sides of the movable portion on a first axis. The movable portion includes a frame-shaped frame connected to the pair of torsion bars and a mirror unit disposed inside the frame. The mirror unit is connected to the frame in each of a pair of connection regions located on both sides of the mirror unit in a direction parallel to a second axis. A region other than the pair of connection regions in a region between the mirror unit and the frame is a space. An outer edge of the mirror unit and an inner edge of the frame are connected to each other so that a curvature in each of the pair of connection regions is continuous when viewed from a direction perpendicular to the first and the second axes.