PURPOSE: To eliminate the need to store or make a note of a password by providing a means which stores character data corresponding to the speech password and a means which displays the character data.

CONSTITUTION: Characters indicated with character codes corresponding to the speech password stored in a character data part 12 are displayed at a display part 15 and the input of a speech is expected. The inputted speech is digitized by a converting circuit 8, and feature data are extracted, syllable by syllable, by a speech analytic composing circuit 9 and temporarily held in a RAM 4. The held feature data are compared with features of the speech password held in the speech password part 11 and when they match each other, it is considered that the correct password is inputted; and the 'password comparing operation' is normally ended and secret operation is enabled. When a discrepancy is decided and a counter value is not ≥'3', the process is returned to the 1st step to perform the reinput of a speech.