Purpose: This study aimed to investigate the level of physical activity and to identify factors related with physical activity for the elderly with Diabetes Mellitus (DM). Methods: The subjects were 154 diabetic outpatient at 3 hospitals located in J city. Data were collected from February 1 to 17 in 2012. Data were analysed using Chi-square test, ANOVA, and logistic regression by SPSS/WIN 18.0. Results: Mean physical activity level per week measured by International Physical Activity Questionnaire (IPAQ) was $2247.01{pm}2533.73$ MET-minutes (minimally active). There were significant differences in the level of physical activity by age, spouse, education, job, admission, duration of DM, and DM therapy. There were significant differences in subjective health status, objective and subjective obesity, satisfaction with physical body, perception of aging, self-efficacy, perceived benefits, perceived barriers, and social support among the inactive, minimally active, and health enhancing physical activity groups. Factors influencing the level of health enhancing physical activity were spouse (OR=10.192), self-efficacy (OR=5.351), subjective obesity (OR=.114), and perceived barriers (OR=.069). Conclusions: The level of physical activity of elderly patients with DM was minimally inactive. Physical activity program enhancing self-efficacy and decreasing perceived barriers, as well as improving the correct perception of subjective obesity is recommended as a nursing intervention.