An upper-level control device includes a communication control unit that transmits a command, which is used after a command that is currently executed and includes an execution order, to an electric motor control device during electric motor control devices respectively perform driving controls of electric motors, and each of the electric motor control devices includes a command storage unit configured to store a plurality of commands, a communication control unit that stores the command received from the upper-level control device in the command storage unit in the execution order, and a command-follow-up control unit that performs a follow-up control of the electric motors based on the command. When the command storage unit is fully filled with the commands, the communication control unit stores a newly received command in the command storage unit by overwriting the newly received command in an area where an executed command is stored.