A bus communication apparatus and a bus communication method are provided, in which data transfer via a bus is not interrupted and no noise is generated in any signal on the bus. The apparatus comprises a bus signal terminal that can be connected to the bus of the external apparatus; a device that communicates with the external apparatus through the bus; a driver that is connected at an input terminal to the bus signal terminal and at an output terminal to the device, has an input impedance much higher than the impedance that the bus signal terminal has with respect to the input terminal and an output impedance much lower than the impedance that the device has with respect to the output terminal, and operates in order to decrease a potential difference between the input terminal and the output terminal; a switch that connects the bus signal terminal to the device; and a control unit that instructs the driver to start operating, then instructs the switch to perform connection and instructs the driver to stop operating, after the bus signal terminal is connected to the external apparatus.