PURPOSE: To execute a command immediately after the input of the command ends without the input of a wrong command.

CONSTITUTION: The character of the command which is inputted from a one- character input device 1 is received by an input character monitor device 2 and one character is taken out of a command storage device 6 according to storage position information stored in a character storage position storage device 7, so that this one character is compared with the inputted character. When those characters coincide each other, the character is stored in a command storage device 4, the storage position of a character to be compared next is taken out of the command storage device 6, and its information is stored in the character storage position storage device 7; if the characters do not coincide each other, a warning device 3 warns the input of the wrong character and a character is inputted again. The comparison is repeated and when a coincident character is inputted, the character is stored in an input command storage device 4; and the command in the input command storage device 4 is read out at the end of the input of the command and the command is executed by a command execution device 8.