An automatic analyzer is equipped with a sterilization mechanism removably attached to an opening of a container that holds a reagent and having an ultraviolet light generation section that radiates ultraviolet light； a suction nozzle removably attached, together with the sterilization mechanism, to the opening of the container； an analysis section adding the reagent drawn in by suction from the container via the suction nozzle to the reagent, and executing an analysis operation； and a control section exercising variable control over an irradiation light intensity of the ultraviolet light generated by the ultraviolet light generation section.
