PURPOSE: To improve the reliability of a lock itself and the portability of a key by using a card on which a square shape, a round shape, or other shapes are printed as a key, and reading the thickness, shape, and number of the shape for unlocking.

CONSTITUTION: When a card 21 is inserted into grooves that are cut in a lock template, a pin 1 enters the hole of the card 21 due to the operation of a spring. The grooves that are cut in the pin 1 are aligned in a line, and sliders 2 are operated by a spring 3. When the three sliders move, a slider 5 moves and a return lever 15 becomes free. Then, when the card 21 is pressed further deeper, the return lever 15 is pressed and the pin of a stopper 8 is pressed down and then a lock bar 11 is released by the force of a spring 13.