This study was carried out to develop an instrument to measure decisional balance of exercise in elderly. The research procedure was as follows: 1) Based on the literatural reviews, the conceptual framework was developed. Then through interview with 20 old people concerning decisional balance of exercise, 35 items were initially adopted. 2) Through content validity analysis of the item by the researchers, 22 items were selected. 3) To test for reliability and validity, data collection was done during the period from June. 1. 2000, to July 31, 2000. The subjects for the test were 249 elderly in community in Seoul. This study utilized Cronbach`s alpha in analyzing the reliability of the collected data and applied factor analysis, item analysis and multitrait-multimethod method to analyze validity. The findings are as follows: 1) The Cronbach`s alpha coefficient for internal consistency was .93 for the 13 items in Pros. and. 73 for 8 items in Cons. 2) The item analysis was based on the corrected item to total correlation coefficient (.30 or more) and information about the alpha estimate if this item was dropped from the scale. 3) As result of factor analysis using principal component analysis and varimax rotation, 2 factors were extracted, and these factors explained 48 percents of the total variance. One item was deleted because of factor loading(less than .40). 4) To analyze the validity, the scale of stage of change for exercise (Marcus et al., 1992) was utilized with this instrument. There were significant mean differences between the stages of adoption according to a elderly`s experience with and intention for exercise in the pros score, the cons score and the decisional balance score. The instrument for accessing decisional balance for exercise of the elderly developed in this study was identified as a tool with a high degree of reliability and validity.