AIM: There is a need for a cognitive function test that is less burdensome to perform cognitive function tests used to date and can detect mild changes in the cognitive function and mild cognitive impairment (MCI). We developed a cognitive function examination using a virtual reality device (VR-E). The purpose of this study was to verify its usability. METHODS: Seventy-seven participants (29 males and 48 females, average age 75.1 years old) were classified according to their Clinical Dementia Rating (CDR). To estimate the validity of VR-E in measuring cognitive function, we used the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment-Japanese version (MoCA-J) scores as benchmarks. The MMSE was performed for all subjects, while the MoCA-J was performed for subjects with an MMSE score ≥20. RESULTS: VR-E scores were highest in the CDR 0 group (0.77±0.15, mean±SD), decreasing for subsequent groups (CDR 0.5: 0.65±0.19, CDR 1-3: 0.22±0.21). The receiver operating characteristic analysis showed that all three methods were able to distinguish CDR groups. For CDR 0 vs. 0.5, the areas under the curve for MMSE/MoCA-J/VR-E were 0.85/0.80/0.70, respectively, and those for CDR 0.5 vs. 1-3 were 0.89/0.92/0.90, respectively. The time required to complete VR-E was approximately 5 minutes. Of the 77 subjects, 12 were difficult to assess using the VR-E due to poor understanding or eye diseases or Meniere's syndrome. CONCLUSIONS: The present findings suggested that the VR-E can be used as a cognitive function test that correlates with existing standard assessments for dementia and MCI.