Abstract: A system for inserting advertisement data into broadcast data and method thereof are provided. The system and method can output advertisement data to a certain portion of a lower end of a screen image of the new channel for a certain time when a current channel is changed to a different broadcast channel according to a viewer's intention while the viewer is viewing a broadcast program, thus minimizing viewer's reluctance to the advertisement output, reducing the burden of an advertiser, and guaranteeing a visual continuity of a broadcast program desired to be searched. Using the present invention, when channels are switched for searching for broadcast programs or when power is turned on or off, advertisement data can be output to the same screen while outputting a pertinent broadcast program, thereby exposing the advertisement data without interrupting the broadcast program.