Provided is a smart servo motor capable of allowing communication without using any unique ID and an actuator assembly using such smart servo motors. A main controller 11 is connected to a plurality of smart servo motors 1-1 . . . 1-N via a single communication path 13, where the main controller 11 can communicate with the individual smart servo motors using their unique IDs. Operating a selector of one smart servo motor 1-u permits communication between the smart servo motor 1-u and the main controller 11 with a special ID such as code “255”. With this communication, the main controller 11 can retrieve the unique ID assigned to the smart servo motor 1-u.