In the past, the elements that determine the movie performance were directors, movie stars, the number of opening screens, on-line ratings or distributing agencies. However, the word-of-mouth effect has changed this trends. So the influence of word of mouth grows more and more strong at this stage of the Internet and smart phones being widely prevalent. I fix my sight upon SNS which is one of the medium of arousing the word-of-mouth effect, and I have a purpose to cast light upon a real example of the influence of SNS on the movie performance. The way is to analyze SNS activities that accompany the process of production and showing of <Sunny>, which is said to have had an beneficial effect of SNS among the enormously successful movies last year. It is relevant to provide a new milestone regarding the movie performance through the successful case of SNS activities by examining the word-of-mouth activities through SNS in the manner of the period division of the pre-release, the early stage of release and the maturity.