An automated analyzer that can effectively reduce contamination of a diluted low-concentration specimen resulting from a high-concentration specimen not being diluted. The automated analyzer includes a specimen nozzle that performs both the function of pipetting a specimen from a specimen container accommodating the specimen and the function of pipetting a specimen diluted by the analyzer, and means for washing the specimen nozzle with a predetermined detergent. When a pipetting process of a high-concentration specimen not being diluted and a pipetting process of a low-concentration specimen diluted by the analyzer are consecutively performed for the same specimen by the specimen nozzle, between the pipetting process of a high-concentration specimen and the pipetting process of a low-concentration specimen, the analyzer performs a washing processing in which the specimen nozzle is washed with the predetermined detergent.