PURPOSE: To achieve an efficient automatic analysis with a colorimetric measurement of a reaction liquid by mounting a plurality of reaction tubes on a reaction tube holder retained rotatably on the plane perpendicular to an inclined shaft centered thereon while the light source and a detector are arranged sandwiching a reaction tube movement path.

CONSTITUTION: A ring-shaped reaction tube holder 7a is mounted on the top of a cylindrical reaction table 7 along an inclined shaft 8 and a plurality of openings are provided to retain reaction tubes 9 along the circumference thereof 7a. Sample liquids are injected sequentially into the reaction tubes 9 from a distribution nozzle 12. A light source 10 is provided inside a reaction table and light irradiates the reaction tubes 9 from a notch 7b provided on a cylindrical body 7. The light transmitting the tubes 9 is detected with a detector 11 provided outside the cylinder 7 to measure emission color, fluorescence or the like. Thus, a sufficient agitation effect can be obtained with such a simple construction.