A mirror driving mechanism includes a plate-shaped base portion, a mirror that is installed at the base portion, and a temperature detecting section that is installed at the base portion and that detects a temperature of the base portion. The base portion includes a thin portion that is disposed away from an outer edge of the base portion and that has a through hole extending through the base portion in a plate-thickness direction of the base portion, a thick portion that is connected to the thin portion, that is thicker than the thin portion in the plate-thickness direction of the base portion, and that extends along the outer edge so as to surround the thin portion, and a first shaft portion extends into the through hole from an outer periphery of the through hole.