This research was performed to investigate the characteristics and determination factors on tertiary hospital inpatients. The used data was the four waves of Korea Health Panel(2008, 2009, 2010, 2011), and the number of subjects was 4,430 cases of tertiary and general hospital admission. The statistical methodology used in the study is the logistic regression model. The significant affecting factors in utilizing tertiary hospital admission were gender, marital status, education, household income, residence region and ICD-10 classification. Man, graduating college/university, married, high-income were socio-economic affecting factors in tertiary hospital admission. Medical need factor of ICD-10 classification and residence region of inpatients was also significant affecting factors in tertiary hospital admission. The 81.4% of inpatients at tertiary hospital had chronic disease and the 12.9% of inpatients readmitted, the 68.2% had a selecting doctor and the only 26.7% of inpatients reinforced by private medical insurance. This study recommended the Korean government to provide proper rule for tertiary hospital admission in order to improve the equity and efficiency of health care system.