A subject observation apparatus of the invention includes: a light-emitting section for emitting a light to a subject an optical modulation section for detecting a scattering angle of a return light from the subject and performing optical modulation on the return light in accordance with the scattering angle and a signal output section for generating a signal to show a state of light scattering in the subject based on the light subjected to the optical modulation by the optical modulation section, and outputting the generated signal.
