Methods: We retrospectively reviewed the medical records of 198 women aged 40–70 years who underwent mass screening for osteoporosis at our hospital between 2016 and 2019. The BMD values and the following data were collected: age, body mass index, fracture history, lower back pain, height loss, kyphosis, history of fragility fracture, family history of vertebral or hip fracture, and menopause. The reliability of each data point for the young adult mean <80% was calculated using discriminant analysis. Variables with large weight coefficients were selected and scored. This scoring tool was examined, and a cutoff score for predicting the young adult mean <80% was determined. Results: Sixty-four participants (32.3%) had a young adult mean <80%. According to the weight coefficients, the following five variables were scored as follows: age ≥60 years 3 points, body mass index <22 kg/m2 3 points, lower back pain 1 point, height loss (cm) 1 point, and menopause 1 point. The area under the receiver operating characteristic curve was 0.738 (95% confidence interval, 0.669–0.807). At cutoff scores of ≥5 and <5, the sensitivity was 82.8%, with specificity of 52.0%. Conclusions The scoring tool performed well for predicting young adult mean <80% among perimenopausal and postmenopausal women in Japan. This tool may be useful to screen for low BMD.