A conversion device for interconversion of wired communication and wireless communication includes a wired IF, a wireless IF, a converter that retains a first MAC address of a communication terminal connected to the wired IF and uses the first MAC address to convert wired communication in which the communication terminal is a destination into wireless communication and convert wireless communication in which the communication terminal is a source into wired communication between the wired IF and the wireless IF, and a controller that receives a communication packet including an IP address and a second MAC address through the wireless IF, and when the second MAC address included in the received communication packet is the same as the first MAC address, sets the IP address included in the received communication packet as an IP address of the conversion device.