PURPOSE: To indicate whether respective keys on a keyboard can be depressed or can not be depressed from outside or software by providing a key selecting means for indicating keys with a fixing function which can be depressed corresponding to indicated key numbers among keys with the fixing function.

CONSTITUTION: When a key initialization request 101 is inputted from a key initializing means 1, key state information 102 whose depression permission information is set to 'depression permission' is outputted as many times as all the keys. When a key selecting means 2 inputs the key state information 102 or key state information 103 outputted from the software, the key selecting means 2 refers to the key number of the input key state information 102 or 103 and selects the key 5 corresponding to the key number among the 1st fixing function key 3 - (n)th fixing function key 5 on the keyboard. Consequently, whether the keys on the keyboard can be pressed or can not be pressed can be indicated from outside or the software.