This article examines whether sex education influences the sexual behavior of young people. Specifically, we analyzed the influence of sex education on the choice of contraceptive behavior by young people, focusing on the perceived usefulness of sex education and concern about pregnancy, with reference to the KAB model of health education.

　The results suggest that the effects of school sex education on concern about pregnancy and contraceptive behavior differed between high school and undergraduate students. The high school students' contraceptive behavior was indirectly influenced by their experience of abortion education in school, mediated by their attitudes toward contraception. The high school students' contraceptive behavior was also directly influenced by their perception of the usefulness of sex education. For undergraduate students, however, sex education at school was not effective. Undergraduate students do not always consciously refer to the knowledge they have acquired so far, not limited to the knowledge obtained through sex education in school.

　In addition, the concern about pregnancy had an effect on contraceptive behavior, and vice versa. Furthermore, after high school students actually choose a contraceptive behavior, they might realize the usefulness of sex education and then use their knowledge to choose their next behavior.