A portable terminal includes a function to detect its own location. The owner of such terminal registers in advance an area in which he expects to be for a given time slot as conditions for operation. The portable terminal verifies its location with respect to the operation conditions set by the owner, and where it is determined that the operation conditions are not met, the portable terminal disables itself, prohibiting its use. Where a pre-registered password is subsequently input, the portable terminal cancels this prohibition. Consequently, if the owner loses the portable terminal while away from home or the office, for example, a third party cannot operate the portable terminal, and moreover, unless the owner-registered password is input, the prohibition is not cancelled, thereby preventing disclosure of the data and other information stored in the portable terminal.