The present invention provides a composition containing afruit body of Agaricus blazei murill or an extract of thefruit body, and an amino acid constituting the ornithine cycleor a salt thereof, wherein the pharmacological activities ofthe fruit body of Agaricus blazei murill or the extract of thefruit body and the amino acid constituting the ornithine cycleor the salt thereof are increased synergistically.According to the present invention, a compositioncontaining a fruit body of Agaricus blazei Murill or anextract of the fruit body, and an amino acid constituting theornithine cycle or a salt thereof in 10 - 100 parts by weightper 1 part by weight of the fruit body or the extract can beprovided.