1. A summary content generation device, which uses digital broadcast signals having video data and subtitle data to generate summary content for a broadcast program, comprising: a subtitle character string extraction unit, for extracting a subtitle character string from subtitle data contained in said digital broadcast signals; a still image extraction unit, for extracting one still image corresponding to said subtitle character string from video data contained in said digital broadcast signals; and a summary content generation unit, for generating summary content, which displays, on a screen, said extracted subtitle character string together with said corresponding extracted still image, wherein said summary content generation unit decides the timing for switching display of the plurality of subtitle character strings and still images comprised by said summary content, based on the subtitle character strings.