Disclosed is a measurement method for a glycated hemoglobin ratio. According to a measurement method for a glycated hemoglobin ratio of the present invention, reagents are easy and convenient to use because of their sequential leakage during the rotation of a cassette, are all discharged by the rotation with no remaining reagent, and are not mixed with each other. Therefore, measurement results are accurate, with fewer errors in the quantities of used reagents and sample blood.