Purpose: This was a methodological study that aimed to develop a measurement scale for aging anxiety among middle-aged women., Methods: In this study, construct factors were extracted, and a conceptual framework was established through an extensive literature review and in-depth interviews with middle-aged women. Under the conceptual framework, 44 preliminary items were constructed, and a preliminary scale of 25 items was completed after two rounds of expert validation and item review. For this study, data were collected from 201 women aged 40~59 years, and the construct validity and reliability of the preliminary scale were verified., Results: To verify the construct validity, exploratory factor analysis was conducted. Four factors containing 19 items were extracted. Concurrent validity of the developed scale was verified with Pearson's correlation analysis. The final scale comprised 4 factors ("Social valueless", "Physical weakness", "Concern about changes in appearance", and "Expectations of old age") and 19 items. The Cronbach's α value was .91., Conclusion: The scale for measuring aging anxiety in middle-aged women developed in this study validly reflected the peculiarities of aging anxiety in middle-aged women, who experience many physical, emotional, and social changes. The scale can be said to reflect the cultural background, as it reflected real experiences gained through in-depth interviews with middle-aged women., Competing Interests: The authors declared no conflict of interest., (© 2019 Korean Society of Nursing Science.)