A mirror device comprises plural mirror elements, each of which comprises a mirror for reflecting illumination light emitted from a light source, a hinge for supporting the mirror placed on a substrate, a hinge structural body for supporting the hinge, and electrodes for controlling a deflection direction of the mirror placed on the substrate, and in each of which the hinge is placed so as to traverse the edge of the mirror or the border with an adjacent mirror. Also enabled is a configuration of a projection apparatus, which comprises the mirror device.