Billing system, mobile terminal, and billing method

To provide a billing system capable of simplifying user's operation and quickly performing a billing process even in the case where there exist a plurality of terminals for billing. A billing system 1 according to the present invention is a billing system for implementing billing by transmitting billing information transmitted from a billing information transmitting terminal 30 to a cellular phone 10, to a billing server 60 on a mobile communication network, in which a service code of a service for which a billing process is allowed is preliminarily stored in the cellular phone 10 and in which, when the billing information is transmitted from the billing information transmitting terminal 30, whether a service code included in the billing information is a service code for which the cellular phone 10 is allowed to perform the process is determined on the basis of whether it agrees with any service code preliminarily stored. When it is then determined that the cellular phone 10 is allowed to perform the billing process, the cellular phone transmits the billing information to the billing server 60 and performs the billing process.