It is desirable to more stably and efficiently transmit light in a housing of a light source unit. A light source unit 13, which emits a laser beam L to a light guide part 40, includes: a unit housing 13b that includes a connector receiving portion 51b detachably connected to a connector portion 51a a light source 30 that is installed in the unit housing 13b and outputs the laser beam L a diffusion part 80 that diffuses the laser beam L output from the light source 30 a condensing lens system 81 that condenses the laser beam L diffused by the diffusion part 80 and an optical fiber 82a that transmits the laser beam L, which is condensed by the condensing lens system 81, to the connector receiving portion 51b. The connector receiving portion 51b optically connects the optical fiber 82a to the light guide part 40.
