An optical measurement apparatus includes a main body base, an optical base movably combined with the main body base, a measurement optical system fixed to the optical base, and an optical base moving mechanism which moves the optical base relative to the main body base. The optical base moving mechanism moves the optical base relative to the main body base between an internal measurement position and an external measurement position. A measurement object position of the measurement optical system coincides with an internal measurement object position within the main body base. The measurement object position of the measurement optical system coincides with an external measurement object position outside the main body base.