Clinical decisions on infectious diseases in terminally-ill cancer patients are often made based on physicians’ and nurses’ personal medical experiences, which may lead to an intra-team conflict. We conducted a qualitative analysis with prospectively gathered, semi-structured interviews in order to identify physicians’ and nurses’ beliefs and perceptions contributing to the variabilities in their attitudes toward patient care and the conflicts during decision-making process. We obtained the following categories with respect to beliefs and perceptions: estimated prognosis; patient’s discomfort due to tests and treatment; agreement to physician’s treatment plan; patient’s and family’s wish for tests and treatment; and patient’s benefits by tests and treatment. The intra-team conflicts resulted from disagreement on patient’s condition, and difficulty understanding mutual intent or opinion among physicians and nurses. Our findings may help improve team-based communication and the quality of care in terminally-ill cancer patients with infectious diseases.