An optical scanning device, having: a substrate main body; two cantilever beams protruded from the respective side portion of one side of the substrate main body; a mirror supported by torsion bars from the respective side, between the cantilever beams; a drive source to causes the substrate main body to vibrate; and a light source to project light onto the mirror, wherein a fixed end of the substrate main body is fixed to a supporting member, on the opposite side from the mirror side, and wherein the mirror resonantly vibrates according to vibration applied to the substrate by the drive source, thereby to change a direction of reflection light of the light projected onto the mirror from the light source according to the vibration of the mirror, characterized in that a Si mirror is attached to and fixed on the mirror.