Since South Korea's 5-year policy of increasing National Health Insurance (NHI) coverage began in 2017, related pharmaceutical expenditures have increased by 41%. Thus, there is a critical need to examine society's willingness to pay (WTP) for increased premiums to include new anticancer drugs in NHI coverage. Participants aged 20-65 were invited to a web-based online survey. The acceptable effectiveness threshold for a new anticancer drug to be included in NHI coverage and the WTP for an anticancer drug with modest effectiveness were determined by open-ended questions. A total of 1817 respondents completed the survey. Participants with a family history of cancer or a higher perceived risk of getting cancer had significantly higher WTPs (RR [relative risk] = 1.17 and 1.21, both P = 0.012). Participants who agreed on adding coverage for new anticancer drugs with a life gain of 3 months had a higher WTP (RR = 1.70, P < 0.0001). These associations were greater among the employed and low-income groups. The adjusted mean of acceptable effectiveness for a new anticancer drug was 21.5 months (interquartile range [IQR] = 19.3 to 24.0, median = 21.9). The WTP for a new anticancer drug with a life gain of 3 months was $5.2 (IQR = 4.0 to 6.0, median = 4.6). The unrealistic expectations in Korean society for new anticancer agents may provoke challenging issues of fairness and equity. Although Korean society is willing to accept premium increases, our data suggest that such increases would benefit only a small proportion of advanced cancer patients.