An automatic analyzer which realizes stable reagent heating and high dispensing accuracy includes a thermostat bath for controlling a reagent or a reaction solution in reaction cells arranged on a circumference of a reaction disk to have a constant temperature; a first reagent dispensing mechanism dispenses a reagent into the reaction cells; a photometer detects transmitted light or scattered light in the reaction cell; and a disposable reaction container for allowing the sample and the reagent to mix and react with each other. The analyzer also includes a second reagent dispensing mechanism with a reagent heating function which dispenses the reagent into the disposable reaction container; a coagulation time detection section; a reaction container temperature control block; a reagent dispensing syringe which is connected to the second reagent dispensing mechanism; and a fluid temperature control mechanism which controls the temperature of an internal fluid of the reagent dispensing syringe.