This invention relates to a pharmaceutical composition for oral administration comprising 4-((1-methylpyrrol-2-yl)-carbonyl)-N-(4-(4-morpholin-1-yl-carbonylpiperidin-1-yl)-phenyl)-1-piperazinecarboxamide, a salt thereof, or a solvate thereof, as an active pharmaceutical ingredient； and at least one acid additive selected from the group consisting of adipic acid, succinic acid, fumaric acid, L-aspartic acid, and L-glutamic acid.
