The purpose of the study is to investigate the conflicts of interest (agency cost) on the formation of fat cat companies between the company's internal or external shareholders and creditors. This paper pattern sample data, taken from the Taiwan Economic Journal and MOPS for 2008 to 2012 for the study period, mining Probit regression analysis found: Conflict of interest (agency cost) between insiders and creditors or outside shareholders is higher, the higher the possibility of the formation of fat cat companies.