A public telephone system includes a plurality of public telephone sets and a center apparatus. Each public telephone set includes a memory for storing a current tariff table used in the speech communication service and a revised tariff table including the tariff information from the center apparatus, a first timepiece unit for setting the time information from the center apparatus to perform a time counting operation, a first data memory for storing the change time information from the center apparatus, a determining unit for determining whether a current time counted by the first timepiece unit reaches a change time stored in the first data memory at a time of call originating, and a tariff processing unit for referring to the current tariff table in the memory to perform the tariff processing when the current time does not reach the change time and referring the revised tariff table in the memory as the current tariff table to perform the tariff processing when the current time reaches the change time on the basis of an output from the determining unit.