Purpose: The purpose of this descriptive study is to search correlation between degrees of depression and cognitive function for early finding out dementia. Method: The measurements of this study were used with specific magazines for ordinary peculiarity in imbecility, Korean type MMSE-K for old aged man designed by Kwon Young Chul(1989) and abridged measurement of old aged people`s depression(Sheikl & Yesavage, 1986). Result: 1. Cognitive function derived from ordinary characters showed considerable discrepancies in statistics. Here are ordinary characters ; gender(T=7.159, P=.000), age(F=31.099, P=.000), education level(F=62.659, P=.000), resident from(F=9.950, P=.000), marriage from(F=13.418, P=.000), body ailment(T=-2.261, P=.024). 2. Results extracted from cognitive funtion and depression by using Person`s relation coefficient showed these data ; depression(R=-.254, P=.000) these data represented inverse relation. 3. There are some prime variables that could predict the degree of cognitive function, in these variables, education(22.8%) showed most great explanation and the next age(6.9%). These variables were included in total data, the explanation presented 29.7%. 4. Lifehood level showed most considerable explanation in predicting depression and here are descending series ; economic status(9.8%), cognitive function(5.3%), These variables were included in total data, the explanation presented 15.1%. Conclusion : The problems of dementia concerned with old aged are issued in respect of social problem. Therefore at the each level, an effort to prevent the dementia, reinforcement of system, continuous research and development of proper program should be performed.