This research aims to consider educational significance and merit of the science lectures by science specialists, focusing on change of interest and motivation of participants, who are consisting mainly of junior high school pupils preferring science, through specialists' lectures organized by "Hiroshima University Kagaku Wakuwaku Project". Consequently, it was clarified that participants have been divided into 2 types; the one is strong in science thinking, and the other is not strong. he former participants have heightened their interest and motivation much more. The latter participants could often appreciate thinking in learning science, however they have reduced their interest and motivation.