The present invention relates to a composition for inhibiting HIV activity comprising the extract of Paecilomyces sp. (Tochu-kaso) J300. More particularly, the present invention relates to a composition for inhibiting HIV activity comprising 3-[5-(methoxy-ethyl)-3,6-dioxo-piperazine-2-yl]propionic acid represented by Formula 1 and 4-methyl-2-[(pyrrolidine-2-carbonyl)-2-amino]pentanoic acid represented by Formula 2 that are extracted from Paecilomyces sp. (Tochu-kaso) J300; and to a medical composition and food composition containing the same. ##STR00001##