To clarify the absolute configurations of antafumicins A and B, which are antifungal substances from Aspergillus niger NH-401, the total synthesis of (2S)-antafumicins was accomplished by starting from (S)-malic acid in 12 steps. Based upon the physicochemical data of the synthetic samples, the absolute configurations of naturally occurring antafumicins A and B were determined as (2R,4S)- and (2R,4R)-4-(3-acetyl-2,6-dihydroxyphenyl)-2-methoxy-4-butanolide, respectively.