To produce anti-malarial drugs, natural products were extracted from 18 species of marine algae by various mechanical methods. Twelve species of marine algae were found to have antiplasmodial activity by inhibiting the growth of the chloroquine-resistant Plasmodium falciparum strain FCR-3 with EC₅₀ values less than 100 ㎍/㎖. The methanol extract of Neoholmeria japonica had the strongest antiplasmodial activity with EC₅₀ value of 62 ㎍/㎖.