To respectively use an input device and an output device in common among plural computer devices.

Output signal receiving parts 16 to 19 respectively receive output information outputted from connected computer devices 5 to 8. An output signal edition part 20 converts the output information received by respective receiving parts 16 to 19 in accordance with the sizes and positions of windows to be displayed on an output device 4. An output signal control part 21 edits the output information converted by the edition part 20 so as to display it on the full screen of the device 4, prepares an output signal to be transmitted to the device 4 and outputs the output signal to the device 4. An input device control part 11 specifies a corresponding computer device out of the devices 5 to 8 from the coordinates of a cursor position inputted from an input device 2 or 3 and transfers input information to a corresponding input information control part out of plural ones 12 to 15. Each of the control parts 12 to 15 transfers the input information to the corresponding computer device.