Purpose: The study was performed to identify the process of change, decisional balance and self-efficacy corresponding to the stage of exercise behavior change based on a Transtheoretical Model in middle aged women. Method: The subjects consisted of 317 women by convenience sampling residing in city B. The collected data were analyzed using one-way ANOVA, Scheffe test, and Discriminant analysis by SPSS/WIN program. Result: The subjects were distributed in each stage of change of exercise behaviors: 53 subjects (16.7%) in the precontemplation stage, 86 subjects (27.1%) in the contemplation stage, 88 subjects (27.8%) in the preparation stage, 51 subjects (16.1%) in the action stage and 39 subjects(12.3%) in the maintenance stage. Analysis of variance showed that consciousness raising (F=24.96, p=.00), environmental reevaluation (F=7.l3, p=.00), self reevaluation (F=19.47, p=.00), dramatic relief (F=15.22, p=.00), social liberation (F=4.26, p=.00), counter conditioning (F=26.44, p=.00), a helping relationship (F=13.l7, p=.00), reinforcement management (F=21.25, p=.00), self liberation (F=27.70, p=.00), stimulus control (F=13.49, p=.00), pros (F=14.40, p=.00) and self-efficacy (F=39.9l, p=.00) were significantly associated with the stages of change of exercise behaviors. Through discriminant analysis, it was found that ‘stimulus control’ was the most influential variable in discriminating the five stages of change. Conclusion: This study can provide the basis of a staged matching exercise program using TTM for more effective and useful intervention.