Background: Dietary Na<sup>+</sup> or Na<sup>+</sup>/K<sup>+</sup> ratio has been reported to be associated with bone mineral density (BMD). However, this remains unclear, and only a few studies have been reported on the Korean population. Therefore, this study aimed to determine the association between dietary Na<sup>+</sup>, K<sup>+</sup>, and Na<sup>+</sup>/K<sup>+</sup> ratios and BMD in middle-aged Korean women.Methods: This study used data from the Korea National Health and Nutrition Examination Survey 2008–2011. A total of 3,690 women aged >50 years were included. Study participants were classified into quartiles (lowest quartile Q1–highest quartile Q4) according to dietary Na<sup>+</sup>, K<sup>+</sup>, and Na<sup>+</sup>/K<sup>+</sup> ratio, and we examined the association of these parameters with BMD. Total femur and lumbar spine BMD were measured using dual-energy X-ray absorptiometry. Multiple linear regression analyses were performed using IBM SPSS ver. 19.0.Results: The mean age was 62 years, and a significant negative trend in the β-coefficient regarding dietary Na<sup>+</sup> was only observed in the total femur BMD. However, the total femur and lumbar spine BMD decreased from Q1 to Q4 regarding the dietary Na<sup>+</sup>/K<sup>+</sup> ratio (P-value for trend: 0.044 for total femur BMD and 0.002 for lumbar spine BMD).Conclusion: A significant negative trend in the β-coefficient for both total femur and lumbar spine BMD was observed regarding the Na<sup>+</sup>/K<sup>+</sup> ratio. Therefore, based on the results of this study, a higher dietary Na<sup>+</sup>/K<sup>+</sup> ratio may be associated with a lower BMD.