Integrated early palliative care (EPC) improves quality of life and reduces psychological distress in adult patients with cancer and caregivers, but attitudes toward EPC have been poorly studied. We aimed to investigate attitudes toward EPC in a nationwide survey of patients with cancer and caregivers. From July to October 2016, we administered nationwide questionnaires examining attitudes toward EPC in patients with cancer (<italic>n</italic> = 1001) and their families (<italic>n</italic> = 1006) from 12 Korean hospitals. When an individual considered EPC unnecessary, the reasons were collected and analyzed. Factors associated with perception of EPC were examined. A majority of patients (84.5%) and caregivers (89.5%) had positive attitudes toward EPC. The most common reasons for deeming EPC unnecessary were that EPC may be an obstacle to cancer treatment (patients: 37%; caregivers: 23%; respectively) or that they were not sure if EPC is beneficial (patients: 21%; caregivers: 24%; respectively). Financial burden as a reason was more evident in caregivers (23%) than in patients (17%). Male gender, age <50, early stage, intensive care unit admission, and not believing that dying people should prepare to practice charity were associated with patients’ negative attitudes. In caregivers, opposition to EPC was associated with not thinking death should be feared, not thinking people should be remembered, and lower educational level. Our findings showed that significant numbers of patients with advanced cancer and family caregivers showed positive attitudes toward EPC. However, more than 10% of participants did not consider EPC necessary. Physicians’ communication with patients and caregivers and financial support could help overcome the barriers of EPC.