The present invention allows a communication mode in which to communicate with a detection section to be easily and conveniently changed in a motor control device. A slave device (90) includes: a network communication section (120) configured to communicate with a PLC (100) via a communication network; an FB signal obtaining section configured to obtain an FB signal from a detection section; and a setting communication section (140) configured to receive communication mode information of an FB through another communication path different from the communication network. The FB signal obtaining section includes a reconfigurable device and is capable of changing a communication mode of the FB signal obtaining section by reconfiguring the reconfigurable device. The slave device (90) reconfigures the reconfigurable device in accordance with the communication mode information in a case where the setting communication section (140) receives the communication mode information.