The present invention provides a bioinformation acquisition apparatus in which when light is radiated to a test object, a flux of light emitted outside from the test object through diffusion effect in the object is reused, improving use efficiency of the radiated light. The apparatus having a light source for radiating a flux of light to the test object and a detector for detecting a signal output based on radiation of the flux of light, includes a reflective member adapted to reflect a flux of light emitted out of the test object when the flux of light is radiated thereto, the reflective member is placed closer to an irradiation area on a surface of the test object than the light source to cover at least a part of the irradiation area from above, and configured to be equal to or larger than the irradiation area.