In a local time amendment system, a navigation apparatus has a clock section to count a clock time (UTC, Universal Time Coordinated) in units of hours, minutes, and seconds based on an atomic clock of a GPS Satellite. In contrast, a cellular phone acquires information on local time wirelessly via a base station, which is connected to a mobile radio communication network. The information on local time signifies a local time of each administrative area, for instance, a country, state, city, etc. The navigation apparatus acquires data in units of hours indicated by an internal clock section of the cellular phone to thereby amend the clock time counted by the clock section with respect to the units of hours to thereby amend the clock time, which is indicated by the clock section, to the local time accurate with respect to units of hours in addition to units of minutes and seconds.