In Japan, social media use by political parties and candidates during election campaign had long been prohibited. However, the rule changed in 2013 and now they can utilize social media such as twitter or Facebook for their election activities. In addition, the first "General Election" introducing new rule were conducted in December 2014. On the other hand, since most of all Japanese politicians had never used social media for their election, there are few literature related to Japanese election and "real" social media use. This means the lack of literature may make evaluation of effective use difficult.
In this research, we focus on candidate’s twitter use during the election campaign and try to clarify usage tendencies of social media by each political party. The result indicates that twitter analysis conducted by news paper companies may have great mistake in terms of definition of target tweets. If usage tendencies of social media are greatly different among political parties, we should re-consider definition of target tweets.
