PURPOSE: To automatically perform the posture correction of a reaction container corresponding to the luminous flux path of a colorimetric measuring light, by providing pawl members to the upper outer peripheral surface part of a support member so as to elastically support the same in a protrusible manner at required inetervals while upwardly protruding the same after the passage of the reaction container to press the rear surface of the end part of the reaction container to transfer said container.

CONSTITUTION: A required number of small bottomed holes 61 are provided to the upper surface 60a of a semi-circular support member 60 by drilling at required intervals and pawl members 63 are provided in said holes in a protrusible manner. When a reaction container 4 reaches a semi-circular part La, each pawl member 63 is received in the small hole 61 to allow the passage of the reaction container 4 but protruded from the upper surfaces 60a of the support member 60 after the reaction container 4 passes and, because the support member 60 is revolved in synchronous relation to a sprocket 6 at the same speed in this state, the pawl member 63 transfers the container 4 to the next stop position, for example, an optical measuring position in a state contacted with the rear surface of the end part 4b of the reaction container 4.