Provided is a pharmaceutical composition for oral administration enabling improved solubility, improved dissolution properties, and improved oral absorbability of (2R)-N-({5-[3-(2,5-difluorophenyl)-2-(1,3-dihydro-2H-benzimidazole-2-ylidene)-3-oxopropanoyl]-2-fluorophenyl}sulfonyl)-2-hydroxypropane imide amide (hereinafter referred to as compound A) or a pharmaceutically acceptable salt thereof, as well as size reduction. The pharmaceutical composition for oral administration contains an amorphous form of compound A or its pharmaceutically acceptable salt, and a polymer.