Safety is top priority in nuclear power plants. Safety cul-ture, which is organizational culture which makes mem-bers of the organization to pay their attention to safety as their priority, is essential to keep safety. It is known that continuous learning activity using accident and incident database is necessary to develop safety culture. Never-theless, the learning activity has not been continued, be-cause of the lack of motivation to use database. In this study, therefore, the authors aim at developing a new method to promote learning activity to use database. First, a time-variation model of motivation for using database was constructed based on an interview with a worker in a nuclear power plant who uses his own database sponta-neously. This model assumes that an attachment, which is an emotional bond to a particular object, was the most significant factor to enhance the motivation for using the database. Second, ¡ÈPraising each other¡Çs data¡É and ¡Èadd-ing original data¡É, were proposed as a method to foster attachment to database. Then, a subject experiment for evaluating the proposed method was conducted. The re-sult showed that the proposed method needs to be modi-fied to include additional factors such as ¡ÈQuality of praise\¡Ç\¡Ç, and ¡ÈDegree of interest¡É.