An automatic analyzer includes a specimen holding section that holds a specimen container for containing a specimen; a specimen dispensing section that dispenses the specimen from the specimen container into a dilution container; a dilution container holding section that holds the dilution container for containing a diluted specimen, which is the specimen that has been diluted; a diluted specimen dispensing section that dispenses the diluted specimen from the dilution container into a reaction container; and a controlling section that, while the diluted specimen dispensing section dispenses the diluted specimen into the reaction container in accordance with a measurement item, causes the specimen dispensing section to perform a cleaning operation of the specimen dispensing section any number of times by using a cleaning liquid.