The old-age income security system in Korea faces three problems: insecurity of basic income, financial insustainability, overaccumulation of pension fund. This article discusses the impact of developmental strategy of the authoritarian developmental state during the rapid industrialization on the design of current old-age income security system: retirement allowance, special pension schemes for public employees, military personnel, and teachers/professors, and the National Pension Sheme (NPS). The pension policy implications of the conservative democratic transition and of the 1997-1998 economic crisis are also mentioned. This paper argues that a structural pension reform based on the NDC (Notional Defined Contribution) principle is the cornerstone of a new old-age income security system which is financially sustainable, guarantees basic income, and free from financial risk of overaccumulated pension fund.