The present invention provides an apparatus for biogenic substance concentration measurement including: a cell including therein a first region, a second region, and a test solution retention space; a light source; a polarizing plate; and a photoreceiver, in which a plurality of first metallic nanorods each having a first antibody on a surface thereof are immobilized on the first region, a plurality of second metallic nanorods each having a second antibody on a surface thereof are immobilized on the second region, the respective long axes of the plurality of first metallic nanorods are aligned in the same direction, the respective long axes of the plurality of second metallic nanorods are aligned in the same direction, the long-axis direction of the first metallic nanorod is orthogonal to the long-axis direction of the second metallic nanorod, and at least one of the polarizing plate and the cell is capable of rotation with an optical axis as the rotation axis.