An analyte treatment apparatus comprising liquid chemical tanks storing liquid chemicals; and a treatment unit carrying out a treatment by supplying the liquid chemicals, so as to facilitate observation. The liquid chemical tanks are made of resin and housed inside a housing unit. Openings are formed in the housing unit. Light projecting means is provided outside of the treatment unit and projects light into each liquid chemical tank through the opening of the housing unit. A colored transparent door is provided to the housing unit and located at the other side with respect to a specific side of the liquid chemical tanks from which light diffusely reflected at the one side and the opposite side of the liquid chemical tank or in the liquid chemical tank can be visually checked, so as to visually check the reflected light. A control unit controls ON-OFF switching of the light projecting means.