To make operatable plural PCs by a common input device without altering the current constitution by giving IDs for infrared communications to plural PC input devices.

A mouse 101 has an ID switching part 102 for switching an ID for infrared communication, an ID registration part 103 which registers the switched ID, an infrared communication part 104 for communication using infrared rays, an input operation part 105 that a mouse has as a conventional input device, and a data storage part 106 where data handled by this mouse are stored. To specify one desired PC to be operated among plural PCs, a button which can be operated with the right thumb of a user is prepared on, for example, the left flank of the mouse and as pressed to change the ID. Consequently, the plural PCs can be operated through the common input device to reduce the operation space and improve the operability.