In a bioinformation acquisition apparatus, a flux of light emitted from a test object through diffusion when the test object is irradiated with light can be reused, improving use efficiency of the radiated light. The apparatus has a light source for irradiating the test object with the flux of light, and a detector for detecting a signal output based on the radiation, and includes: a reflection-type polarization element adapted that at least a part of the flux of light from the light source can be transmitted through, and a flux of light emitted from the test object by the radiation can be reflected, in which the reflection-type polarization element is disposed at a position opposite to an irradiation area of the light on the surface of the test object to cover the irradiation area.