Inquiry about information on a CM can be made based on a feature of that CM, and a server can be inquired about a CM which meets a condition such as keyword, thereby permitting the user to view his desired CM. Detecting a commercial message from a television broadcast, calculating a feature of the detected commercial message and accepting input information appendant to the commercial message, a CM information server creates a data base in which the calculated commercial-message feature and commercial message-appendant information are associated with each other. In response to a request for a commercial message search in which a keyword sent from the user via a network is taken as a key, the CM information server searches the data base for a commercial-message feature and sends the commercial-message feature detected in the data base to the user via the network. The user calculates a feature of the commercial message detected in the television broadcast to select a commercial message whose feature is coincident with the commercial-message feature sent from the CM information server. Also, in response to a request for commercial message-appendant information sent from the user via the network, the CM information server searches the data base on the basis of the commercial-message feature as a key to read commercial message-appendant information whose feature is coincident with the feature detected in the data base and sends it to the user via the network.