Twitter, one of micro-blogging services, was focused on by the effect of US President Obama's speech in the world in 2008, and the number of its users is increasing. Researches in recommendation method with respect to who should be the proper user to follow can be classified into two types; i.e. collaborative filtering using the followee/follower relations, and content-based filtering focusing on the contents similarity among users. However, these recommendation methods reveal shortcomings, in that they do not regard user involvement, namely the extent of communications among users. In order to include the factor of user involvement in recommendation method, a new type of recommendation system will be proposed.