Abstract: Disclosed is an information processing apparatus which includes a processor, one or more input/output devices and an input/output bus for connecting the processor to the input/output devices. A bus connector is included for expanding the input/output bus to an external device. A first switch is used for electrically disconnecting bus signals that are carried by the input/output bus to corresponding connector pins of the bus connector. A second switch is used for electrically grounding the connector pins in the bus connector. The apparatus further includes switch control means for controlling the first and the second switches. When no external device is connected to the bus connector and the connector pins are exposed externally, the first switch is opened to cut off bus signals and to prevent the transmission of high frequency signals to the connector pins.