A light source unit includes a heat-dissipation member having positive expansibility that volume is expanded with an increase in temperature, the heat-dissipation member having a through-hole, a heating component having a heating component body and a pin terminal, the heating component body fixed to the heat-dissipation member in one opening side of the through-hole, the pin terminal connected to the heating component body, and inserted through the through hole and protruding from the other opening side of the through-hole of the heat-dissipation member a substrate fixed to the heat-dissipation member in the other opening side of the through-hole and having a wiring connected to the pin terminal, and a buffering member having negative thermal-expansibility that volume is contracted with an increase in temperature.