To connect a plurality of types of notebook type personal computers of different size to a function extension device respectively without altering the structures of the notebook type personal computers.

The function extension device 1 is provided with a slide moving mechanism part 6 on its main-body cover part 4. This slide moving mechanism 6 can move forward and backward when unlocked with a slide lever 7. Two styles wherein the slide moving mechanism part 6 is slid backward and stored in the main-body cover part 4 (before movement) and the slide moving mechanism 6 is moved are made available to connect notebook type personal computers of different size to the single function extension device.