To provide a game system which can directly reflect the action of a player on a game wherein a large number of input operations of various kinds can be recognized by the game system based on the action of the player.

A player is required to perform an input operation to cover the entire front surface of a screen of a monitor 10. A plurality of light emitting and receiving modules 20, 22 are disposed to give and receive light at the front of a monitor screen to constitute a coordinates sensing device for sensing the size and coordinates of a covering matter (finger or palm) covering the screen of the monitor. If the player has performed a finger input or palm input is checked according to the size of the covering matter. The kinds of the input operation is checked based on the difference in these input methods.