An observation device according to an embodiment of the present technology includes a first polarization section, a second polarization section, a rotation control section, and a calculation section. The first polarization section irradiates a biological tissue with polarization light of a first polarization direction. The second polarization section extracts a polarization component of a second polarization direction that intersects with the first polarization direction, from beams of reflection light that are the polarization light reflected by the biological tissue. The rotation control section rotates each of the first polarization direction and the second polarization direction such that an intersection angle between the first polarization direction and the second polarization direction is maintained. The calculation section calculates biological tissue information related to the biological tissue on the basis of a change in intensity of the polarization component of the second polarization direction according to rotation operation performed by the rotation control section.
