The purpose of this study was to examine the awareness and experience of extramarital relations across individual and familial variables of married men and women. Data for this study were 600 married men and women who were recruited the respondents through internet site. Results of this study were as follows; 1) Most of married men and women were regarded extramarital relations types(emotional connections, short-term relationship such as prostitution, sexual intercourse except a prostitution, one-night stands, physical connections, letter chatting with multimedia, video chatting with multimedia), By gender men had more permissiveness attitudes about extramarital relations type than women, 2) There were significant differences in the awareness and experience of extramarital relations types across variables(sex, age, education level, income, occupation, religion, marriage duration). 3) Married men reported that they experience(emotional connections, sexual intercourse, physical connections, letter chatting with multimedia, video chatting with multimedia, infidelity ideation, infidelity attempts) more extramarrital relations types than married women. There were significant differences in the experience extramarital relations types across variables.