The use of Twitter by citizens during catastrophic events is increasing with the availability of Internet services and the use of smartphones during disasters. After the Great East Japan Earthquake on 2011, Twitter was flooded with lots of disaster information, including misinformation that have been widely spread by retweet. Accordingly, we developed a questionnaire to investigate factors influenced people decision making to retweet disaster information they read from Twitter in disaster situations. We developed a questionnaire using brainstorming and KJ method and conducted a user survey (n =57) to test the questionnaire items. Then, we analyzed using exploratory factor analysis and as a result, five factors derived from 38 question items which are: 1) Trustworthy information, 2) Relevance of the information during disasters, 3) Willingness to supply the information, 4) Importance of the information, and 5) Self Interest. However, there are 7 question items that need revision based on the results of the factor analysis. In this paper, we discuss the method we used to design the questionnaire and the result of the factor analyses of the questionnaire testing.