To provide a technique for fusing advertisements in a broadcast and a network among a plurality of advertisement media and in particular, a technique for obtaining a high advertisement effect by synchronizing the advertisement timing. Provided is a network advertisement transmission method which transmits advertisement data to be outputted in a user terminal device. The method uses an advertisement information database (121) containing in advance: at least an advertisement content of the advertisement transmitted on a broadcast medium such as a television and advertisement information on the broadcast time stored in storage means; and an advertisement condition database (122) containing corresponding advertisement data and its transmission condition in accordance with the advertisement content in stored in storage means. The transmission condition includes at least a condition relationship between advertisement information and the current time. When the current time acquired from a clocking unit (101) by the advertisement transmission unit (105) satisfies the transmission condition, the advertisement data is transmitted to the user terminal device via a network.