1. An on-vehicle handsfree system comprising: a car device that includes, at least one of a microphone, a speaker, a camera, and a display as car peripheral units, first communication means that holds wireless communication with the mobile terminal, and attribute information notification means that notifies the mobile terminal of attribute information via the first communication means, the attribute information for identifying the car peripheral units; and a mobile terminal for at least one of wireless video communication and wireless audio communication via a communication network, the mobile terminal includes, at least one of a microphone, a speaker, a camera, and a display as mobile terminal peripheral units, second communication means that holds the wireless communication with the car device, attribute information obtaining means that obtains the attribute information from the car device via the second communication means, and replacement control means that has the car peripheral units replace corresponding mobile terminal peripheral units according to the obtained attribute information when the mobile terminal holds the wireless communication via the communication network.