Since the bill on basic old age pension proposed by the ruling party and the government has passed through the National Assembly, and the ruling party and the main opposition party agreed on carrying the temporary bill on National Pension Reform in April 2007, in Korea we have a growing prospect of the success in National Pension Reform which has started in 2003. But regardless of whether the National Pension Reform bill will pass or not in the National Assembly in 2007, it is believed that additional reform will be needed to strengthen the financial sustainability of National Pension System with discussion about a long-term pension finance structure of National Pension. This study presents a funded Defined Contribution type individual account program as an effective and feasible reform model for the case that a partial funded pension system with a high level of reserve is considered as an optimal long-term pension finance structure of National Pension System. The reform model includes the program for decentralized decision on asset portfolio, the introduction of a default fund for passive account holders, the introduction of the minimum guarantee pension to reduce market risk inherent in asset management.