A self-position detecting unit detects a self-position. A time calculating unit calculates a time of a time zone where the self-position detected using the self-position detection unit exists. A time display unit displays the time calculated using the time calculating unit. A display control unit causes the time display unit to display time of the first time zone where the self-position exists continually in an area in a second time zone, which is adjacent to the first time zone, when determining that the self-position moves into the second time zone. The area has a predetermined width from a boundary between the first time zone and the second time zone. The display control unit further causes the time display unit to display time of the second time zone when determining that the self-position moves beyond the area.