To identify osteoporosis and examine the relationship between health behavior and the self-efficacy of middle-aged women, a descriptive survey was conducted. The subjects were 465 healthy female residents of Kyunggido, Korea, who underwent ultrasound measurement and a health examination at the Kangmeung-Ci Health Center between July and August 2000. They were 40 to 60 years old, with a mean age of 46.7 years. The subjects completed a self-reported questionnaire that consisted of seven items concerning health behavior and twelve items concerning self-efficacy related to osteoporosis. Bone density was evaluated from ultrasound measurements of the right heel. All the data were analyzed using the program SAS-PC. The study found that the mean T score related to bone density was -1.30, and ranged from -3.52 to 3.06. Based on the T score, 74.8% of the subjects were normal, 12.9% had osteopenia, and 12.3% had osteoporosis. The mean osteoporosis self-efficacy score was 41.17 and ranged from 12 to 60. Osteoporosis self-efficacy differed significantly with health behavior related to health supplementary food (t=5.63, p=.018), exercise (t=6.65, p=.010), alcohol drinking(t=10.80, p=.001), and smoking (t=10.23, p=.001). A community-based health promotion program should be developed to prevent osteoporosis in middle-aged women.