I, as a university associate professor and an ex-journalist, have appeared on several TV news and information programs as a commentator. Why are commentators necessary for such programs? There are two different types of commentators: experts such as university professors and non-experts like TV celebrities. What different roles do they play? This article centers on my experience as a commentator and analyzes roles of university professors who act as commentators by interviewing TV producers and reporters who have been in charge of producing those programs. Separately, the article also tries to find out how university professors affect their universities when they appear on the programs.専攻: ジャーナリズム論