This case report was conducted by the field method approach. The writer was the primary nurse taking care of a boy newly diagnosed with acute myeloid leukemia and his father. Content analysis was applied to fifteen process recordings. The purpose of the report was to identify the role conflict of the father during his coping process. Four kinds of role conflict experienced by the father were found to be (1) a protector conflict; (2)a provider conflict; (3)an authority conflict; (4)a hope keeper conflict. The nursing interventions included: (1)encouraging the appropriate parenting care; (2) providing information and consultation abont care to the father; (3) discussing with the mother how to support and work together with father; (4) consulting social worker for assistance. With appropriate nursing support and medical team cooperation, the reaction of the role conflict in the father can be alleviated, and both father and child can have better adjustment to the ongoing treatment.