Curve number (CN), originally developed, compiled by ‘The Natural Resources Conservation Service (NRCS)’, and has been widely used throughout the world. However, there is the uncertainty of CN derived from the use of antecedent moisture condition (AMC)/Antecedent Runoff Condition (ARC). As in Korea where nearly 70% covered by mountainous area, it is still not sufficient handbook precedent to guide or support the estimation of AMC/ARC. The failure to develop formal criteria of applying AMC/ ARC will be a gaping profession and results not only in uncertainty of CN estimation in particular, but also in designing appropriate structures in Korea as a whole. This paper is aiming at presenting a critical review of AMC/ARC and deriving a procedure to deal more realistically with event rainfall-runoff over wider variety of initial conditions. Proposed methods have been developed. It is based on modifying estimated runoff to observed runoff with coefficient of determination and then applying different algebraic expression with the verification of AMC by antecedent rainfall table of NEH-1964. Clearly indicated from 12 years period analysis and 2 years period of verification, normalized root mean square error, RE and E are best described by the application of algebraic expression by Arnold et al. at the value of 0.8950, 0.9460, and 0.0244 respectively for AMC condition and 1.3799, 0.9642 and -0.0197 respectively for ARC condition. Therefore, Arnold et al. algebraic equation is the best representation criteria of AMC and ARC. This algebraic expression might be applied properly considering South Korea condition.