The automatic analyzer includes: a member to be washed, such as a probe or a stirrer for contacting and stirring a liquid; a wash station in which the member to be washed is washed with a washing liquid; and a measuring part that measures an optical characteristic of an evaluation reagent contained in a reaction cell. A control unit brings the member to be washed that has been washed in the wash station into contact with the evaluation reagent, causes the measuring part to measure the optical characteristic after contact with the evaluation reagent, and calculates the amount of the washing liquid carried into the reaction cell by the member to be washed, based on the measured optical characteristic.