Abstract: A concentration measurer for measuring the concentration of turbidities in object liquid by detecting the diffuse reflection light of a laser beam emitted to the object liquid, comprising a concentration detecting part formed by bundling a plurality of optical fibers for laser beam emission and a plurality of optical fibers for laser beam receiving. In this measurer, a body part having an emitter and a receiver for the laser beam and the concentration detecting part can be formed separately from each other, and the body part and the concentration detecting part can be connected by flexible optical fibers. By this measurer, a concentration up to a high turbidity concentration can be measured with high sensitivity and, when the concentration detecting part is formed separately from the body part, the concentration detecting part can be easily installed even in a restricted area and an adverse environment.