Purpose: The purpose of this study was to examine the cognitive function and degree of dementia patient by doing clock drawing test and to explore the relationship among other dementia screening test. Method: The study subjects were 94 dementia in patients department. The data was collected by face to face interview by clinical psychologist from January 2007 to February 2008. The tools were Clock Drawing Test, K-MMSE, K-3MS and CDR Scale. Results: 1) The average score of CDT was 5.13 (2.54), of K-MMSE was 20.53 (4.85), of K-3MS was 61.66 (16.46), and of CDR was 1.2 (.72), those scores showed dementia. 2) There was a statistically the significant difference in CDT (F=2.83, p=.043) and CDR (F=2.00, p=.008) by age. CDT has shown the differences by gender (t=-2.42, p=.018) and education (F=7.66, p=.000). 3) There were significant relationships between CDT and K-MMSE (r=-.294. p=.004), K-3MS (r=-.335, p=.001), and CDR (r=.286, p=.008). Conclusion: It is believed that using CDT which measures the visuospatial ability of dementia patients and K-MMSE which assesses an ability of language and orientation and K-3MS at the same time helps examining the beginning and the progressive degree of dementia more easily and objectively.