To provide a light source device capable of surely avoiding generation of faults due to diversion or abuse of a light source part, to provide a lighting device using the light source device, to provide a monitoring device, and to provide a projector.

The light source device is provided with a semiconductor laser array 11 as a light source part supplying light, a support part 12 supporting the light source part, a light source cover 17 as a coating part covering the light source part, bonding wires 14 as wiring parts connecting a flexible board 13 as a current supplying part supplying current to the light source part and the light source part, and a blade part 16 arranged so as to penetrate a position at a side of the support part 12 against the wiring parts as well as the coating part.