A light source module includes light source having a light emitting element, a stem configured to support the light emitting element, and a terminal, one end side of which is electrically connected to the light emitting element, a wiring portion to which the other end of the terminal is electrically connected and which is configured to electrically connect the terminal to an external power supply terminal, a connection portion configured to fix the wiring portion and the other end side of the terminal by a connection member, and a thermal diffusion member disposed between the stem and the connection portion and thermally connected to the light emitting element, the terminal has a bent portion which is deformed in accordance with dimensional change in at least one of the thermal diffusion member, the terminal, the wiring portion and the connection member.