An optical measurement apparatus 1 includes a light source that supplies illumination light having at least one spectral component, an illumination fiber 5 for guiding the light supplied by the light source and emitting the light to the scattering medium, a light receiving fiber 7, 8 for receiving returned light from the scattering medium at a tip thereof and guiding the returned light to a base end thereof, a detecting unit 24 that detects light output from the base end of the light receiving fiber, an analyzing unit 27a that analyzes a property of the scattering medium based on a detecting result obtained by the detecting unit, and a switching unit 4 that switches between total areas of emission regions from which light is emitted, at an end face of the illumination fiber.
