”Powerlessness” is a common and serious health problem in diverse clinical settings, especially in chronic illness. The purposes of the study were to identify the essential defining characteristics of ”powerlessness” and establish the reliability and construct validity for it. An evaluation questionnaire for defining characteristics of ”powerlessness” was designed to interview 62 congestive heart failure patients. Clinical assessment was carried out by observation, measurement, semi-structure interview and patients chart. Results of the study showed that the 15 defining characteristics have a high coefficient alpha (.87) and a significant average inter-item correlation (.18). Construct validity of the total scale of 15 items was represented by factor analysis. The three factors describing the subconcepts of ”powerlessness” were labeled as ”inadaptation”, ”malcontent”, and ”incuriosity”. The reliability and construct validity were acceptable. The study concluded that the established 15 defining characteristics were homogeneous for ”powerlessness”， three subconcepts of defining characteristics were able to be identified, and the identified 10 essential defining characteristics were homogeneous and could be a reliable instrument for prompt diagnosis of ”powerlessness”