This study examined market size of private health insurance premium and individual characteristics associated with the market size change in Korea, using wave 1 (2008) and wave 2 (2009) of Korea Health Panel. The market size was 24.4 trillion Korean won in 2008 and 26.9 trillion in 2009. The increase rate of private health insurance premium among those who were the elderly, single, or the poor was higher than that among their counterpart respectively. Health status and utilization were insignificant in determining the increase rate of private health insurance premium. These findings were more obvious among the uninsured in 2008 than among the insured in 2008. The increase of private health insurance premium in Korea imply the increase of willingness-to-pay for health risk through private sector. The authors suggest policy intervention for accessability to health care for the underprivileged and weak through enlargement of Korean social health insurance benefit.