The diversity of sexual norms and values has increased in recent decades. At the same time, issues relating to adolescent sexual behaviors have also increased year by year. Although sex education which focuses on disease and pregnancy prevention may succeed in reducing the occurrences of these negative issues, it does not necessarily succeed in encouraging development in a positive direction. Foucault's genealogical research into ancient Greek and Roman ethics resulted in his ethics of the care of the self. This paper explores this ethics of the care of the self on the five dimensions of self-cultivation, self-constitution, physical health, marital fidelity and love loyalty. The implications for sex education in junior high schools are then considered in relation to this ethics. Implications include: 1. helping individuals to foster self-cultivation and to constitute themselves as ethical subjects; 2. promoting the concept of a regimen which is good for both the body and the mind; 3. enhancing the belief in marital loyalty and equality; 4. developing a new erotic concept of the ethical subject. Finally, this paper offers conclusions and suggestions in accordance with the results of the research.