A light source unit for a lighting tool for a vehicle includes a circuit board on which a light emitting element is provided and a socket main body having a board attachment section to which the circuit board is attached and a connector section electrically connected to the circuit board via lead terminals, wherein the board attachment section has a fixing terminal configured to fix the circuit board, and the circuit board has first hole sections, into which the lead terminals are inserted, and a second hole section, into which the fixing terminal is inserted, and is attached to the board attachment section by the lead terminals being fixed to a periphery of the first hole sections and the fixing terminal being fixed to a periphery of the second hole section.