In a first optical measurement device, light which is output from a light source is subject to linear polarizing in a polarizing unit, and is input to a test object A. Transmitted light which has passed through the test object A is orthogonally separated in an orthogonal separation unit, and the light which is orthogonally separated in the orthogonal separation unit is received in two light receiving units. In addition, amount of light of the transmitted light is determined by a control unit, and a difference between received light levels which are received in the light receiving unit is normalized using the amount of light which is determined in a transmitted amount of light determination unit, and then the angle of optical rotation is calculated by the angle of optical rotation calculation unit.