A data processor which can flexibly control bandwidth settings and setting changes is provided. The data processor controls bandwidth allocation to electronic devices participating in a communication network. The data processor has a communication section used to communicate with the electronic devices and a bandwidth management section which performs control to variably allocate, based on requests from the electronic devices, bandwidths to be used for communication by the electronic devices. In cases where an additional device is added to the communication network and an adequate bandwidth cannot be allocated to the additional device, the bandwidth management section requests another electronic device transmitting video data of a resolution higher than corresponding to the user's intention to change its data format so as to allow an adequate bandwidth to be allocated to the additional device.