Numerous studies have reported that physical activity and exercise training has beneficial effects in not only healthy elderly individuals, but also patients with mild cognitive impairment and dementia. Although various types of exercise appear to present positive effect for cognitive function, there is no definite exercise guideline as treatment or disease modifying strategies in dementia. The purpose of current article is to review the literatures related to the effect of exercise on cognitive function and to suggest the therapeutic exercise strategies in patients with dementia. Further prospective, longitudinal investigations using this exercise guideline should be warranted to prove the beneficial effects of exercise on cognitive function in patients with dementia.