This paper aims to investigate the relationship between the ownership structure and firm value in Korea Securities Market that focuses on the largest shareholder and the related parties’ holdings by using within transformation in fixed effect regression model for 454 listed companies from years 2011 to 2015. The estimations exploit robust covariance matrix estimators by controlling the heteroskedasticity. The results of the analysis imply there were the negative relationship between the largest shareholder and the related parties’ holdings and firm values which suggest the hypothesis of the managerial entrenchment.