Dementia is a condition where there is a decline in global cognitive function or intellectual decline, which causes disturbances in the functions of daily life. One of the non-pharmacological management of dementia is brain exercise. The purpose of the study was to determine the effect of brain exercise on cognitive function in the elderly with dementia at UPT Pesanggrahan Pmks, Mojokerto Regency. This research is a pre-experimental method with a one-group pre-test post-test design approach. The population in this study were all the elderly at UPT Pesanggrahan Pmks Mojokerto Regency totaling 49 people. The sampling technique used is a non-probability sample using a purposive sampling technique with a sample of 15 people. The research instrument used a MMSE questionnaire (mini mental questionnaire) and an observation sheet. The results showed (40.0%) 6 respondents had poor cognitive scores before doing gymnastics and after doing yoga, 2 respondents with poor cognitive function scores reduced (13.3%). normal, Based on the results of the paired T-test, the results obtained are P-Value = 0.000 (P