The Japanese government has implemented a new screening program to promote measures to avoid worsening lifestyle-related diseases and frailty among the older population. In this effort, the government formulated a new health assessment questionnaire for the screening program of old-old adults aged ≥75 years. The questionnaire comprises 15 items, of which 12 address frailty, two address general health status, and one addresses smoking habits. This study examined the construct validity of this questionnaire, using the explanatory factor analysis (EFA) and confirmatory factor analysis (CFA). The data used in this study were drawn from a mail-in survey conducted in 2020 as part of the Septuagenarians, Octogenarians, Nonagenarians Investigation with Centenarians study. A total of 1576 respondents (range, 78–99 years of age) were included in the study. Although the EFA did not show an interpretable factor structure of the questionnaire with 15 items, the CFA using only 12 frailty-related items showed the goodness of fit for a higher-order factor “frailty”, and the five frailty-related sub-factors model was acceptable. These results suggest that the total score of the 12 frailty-related items in the questionnaire can be used as an indicator of the degree of “frailty