Background : Nasopharyngeal cancer is a malignant tumor that attacks the nasopharynx, in Indonesia nasopharyngeal cancer ranks 4th after breast cancer, cervical cancer, and lung cancer. The incidence of nasopharyngeal cancer which is quite a lot is of course influenced by several risk factors. Purpose : To find out the factors that cause nasopharyngeal cancer in Yogyakarta. Methode : This research uses qualitative methodology phenomenology. Informants in this study amounted to 12, taking the number of informants based on purposive sampling technique. The instrument of this study used an in-depth interview guide that contained questions about the factors that cause nasopharyngeal cancer. The validity test of the data uses several data checking techniques, namely: source triangulation, peer debriefing, and member checking. Analysis of this study using open code 4.02. Result : The results showed that the factors that caused nasopharyngeal cancer were smoking, knowledge of informants who were less related to nasopharyngeal cancer, foods containing nitroxyamine and carcinogenic, family history of cancer and tumors, history of ARI and herpes, occupational health, and drug consumption or without a doctor's prescription. Conclution : Nasopharyngeal cancer causing factors occur due to various factors that can activate EBV and damage DNA so that the body is susceptible to exposure to carcinogenic substances.