The main purpose of this study was to investigate factors that affect bone mineral density (BMD) in Korean adult women ($20{sim}80{leq}yr$). Data on BMD, anthropometric (height, weight, body mass index, waist circumference, and body fat), and biochemical (total cholesterol, vitamin D, and alkaline phosphatase) measurements were obtained from the Fourth and Fifth Korea National Health and Nutrition Examination Surveys (KNHANES, 2008~2011). Overall, the BMD of subjects had decreased from year to year: the T-scores decreased from 0.657 (2008~2009) to 0.295 (2010~2011) in 40~49 yr group and from 0.076 to -0.081 in 50~59 yr group. Age was negatively associated with BMD (T-scores of 0.388 in 20~29 yr group and -1.952 in ${geq}80yr$ group for total femoral). BMD continuously increased with increased weight and body mass index (BMI). High values of total cholesterol (T-scores of -0.005 in 201~229 mg/dL group and -0.094 in ${geq}230mg/dL$ group for total femoral) and alkaline phosphatase (T-scores of 0.481 in ${geq}102IU/L$ group and -0.674 in ${geq}336IU/L$ group for total femoral) were associated with lower BMD. Overall height, weight, and BMI were positively associated with BMD, whereas total cholesterol and alkaline phosphatase (ALP) were negatively associated with BMD. Findings of the present study show that bone loss may be associated with various factors such as age, weight, BMI, total cholesterol, and ALP et al., and that much attention should be paid to bone health of adult women. Therefore, practical and systematic programs are required to improve the BMD of adult women as well as to maintain healthy bone levels.