A nursing activity classification for hospitalized patients was performed based on an article review regarding nursing definition and nursing activity classification system. The study was conducted as follows: 1) Taxonomy was developed by the research team through the Delphi process and review article. The taxonomy consists of four nursing processes, (assessment, diagnosis, intervention and evaluation) and twelve nursing activity domains space (resperation, nutrition, elimination, exercise/alignment maintenance, comfort, hygiene, safety, spiritual support, counseling/ education, medication, communication, patient and information management). 2) First, nursing activities of the intervention process were listed and then classified by the nursing process of assessment, diagnosis, intervention and evaluation. The list consists of twelve nursing activity domains and 136 nursing activities. 3) A pilot study was conducted in two hospitals to verify validity and appropriateness of nursing activities. 4) The content validity index, which was calculated by 6 clinical practice experts, was 0.95. Also, a nursing activity classification system should also be developed in the department of community nursing and home health care nursing.