Information polarization has the potential of developing into various problems such as opposition conflict. In this study, we analyzed the information polarization was caused in Japan by using Twitter data during the 48th Lower House Election in 2017. We succeeded to separate the opposite opinion such as political criticism (liberal) and political supporting (conservative) by using tweet networks based on users’ retweets. Furthermore, in the result of analysis focusing users who retweet the tweets, it suggests that the liberal users did not retweet conservative tweets although the conservative users retweeted a few liberal tweets. Also, users cannot even access the tweets which have a different opinion. We indicate that the relation of follower-followee causes selective contact since users’ opinions are related to the followees’ them by the correlation coefficient of 0.903.