This study sought to determine which factors among the indicators of socioeconomic status have the most influence on physical, mental and social functions, and on subjective well-being, all of which are components of successful ageing. A representative random sample of 1825 persons aged 65 years or older was surveyed by face-to-face interview. Socioeconomic status was measured by educational level, family household income, personal income and property ownership. The factors measured were chronic diseases, activities of daily living (ADL) for physical functioning, history of mental disease, Mini-Mental Status Examination questionnaire (MMSE) scores for mental functioning, social activity participation per week for social functioning, and the Philadelphia Geriatric Center Morale Scale (PGCMS) for subjective well-being. Multiple logistic regression analyses were performed. Education level was the most important factor in physical and mental functioning, whereas personal income was the most important in social functioning. Educational level, household income and personal income were significantly associated with subjective well-being as assessed by PGCMS scores. Subjects who demonstrated successful ageing were more likely to have a higher education and higher personal income. The results point to the importance of focusing on disparities in each component of successful ageing, which may point to appropriate health-promotion strategies for eliminating inequality in successful ageing.