Purpose@#This study investigated knowledge of and attitudes toward advance directives (ADs) among middle-agedwomen in South Korea, their willingness to write ADs in the future, and the factors related to knowledge of and attitudes toward ADs. @*Methods@#Data were collected using a self-administrated questionnaire completed by 154 middle-agedwomenaged 50 to 64 from February to March 2020. The questionnaire asked about participants’ knowledge of and attitude toward ADs, willingness to write ADs in the future, experiences with life-sustaining treatment within their families, experience making decisions about life-sustaining treatment, and demographic characteristics. @*Results@#Scores for both knowledge of and attitude toward ADs were relatively high. About 60% of participants gave wrong answers when asked if attorneys were required for writing ADs. A higher knowledge score was significantly associated with a higher attitude score (r=0.227, P<0.01).The women were more likely to be willing to write ADs in the future when they reporteda middle income level rather than a lower income level (odds ratio [OR]=5.952, P<0.01), considered themselves unhealthy (OR=5.873, P<0.01), and graduated college or higher (OR=4.096, P<0.05). Furthermore, womenwhothought that ADs would have an impact on treatment (OR=1.869, P<0.05) and on their families (OR=1.447, P<0.05) were morelikely to be willing to write an AD. @*Conclusion@#This study shows that wrong information about ADs persists among middle-agedwomen, and significant factors associated with knowledge of and attitude toward ADs were identified. Targeted education programs about ADs need to be developed for middle-agedwomen.