This study investigates the relationship among media coverage, retail investor sentiment and stock return in Taiwan stock market from December 2003 to December 2013. We also examine whether the relationship would change on different market state or not. The result indicates that first, news frequency has positive influence on excess stock return, and stock returns of small firms react to news frequency more slowly than big firms. Secondly, retail investor sentiment has a partial mediation effect on the path of news frequency to stock return. Thirdly, the news frequency of the big-firm portfolio has negative influence on the excess stock return of the small-firm portfolio, especially during a bull market.