Mild cognitive impairment (MCI) is not just a prodrome to dementia, but a very important intervention point to treat Alzheimer's disease (AD). It has long been known that AD patients have a higher frequency of falls with some gait instability. Recent evidence suggests that vestibular impairment is disproportionately prevalent among individuals with MCI and dementia due to AD. Here we have developed a useful method to evaluate balance capability as well as vestibular function using Nintendo Wii balance board as a stabilometer and foam rubber on it. The new balance capability indicator, termed visual dependency index of postural stability (VPS), was highly associated with cognitive impairment assessed by MoCA, and the area under the receiver operating characteristic (ROC) curve was more than 0.8, demonstrating high sensitivity and specificity. Thus, it was proved that VPS helps screen individuals with MCI at an early and preclinical stage with high sensitivity.