A service providing system for verifying a source of information is disclosed. The system is composed of a computer network, at least one server connected to the computer network and sending information including a specified mark to the computer network, a communication carrier connected to the computer network and adding, when information received from the computer network includes the specified mark (Trusted Site Indicator tag), specified data (Trusted Site Indicator data) used to identify the server which has sent the information to the information, an mobile device provided with a proprietary display area which can not be edited or tampered by an unauthorized person, making wireless communication with the communication carrier and displaying the TSI (Trusted Site Indicator) data on the proprietary display area when receiving information includes the TSI (Trusted Site Indicator) data.