Disclosed is a dry powder pharmaceutical composition for inhalation, which is useful for prevention and/or treatment of influenza virus infectious diseases.Specifically disclosed is a dry powder pharmaceutical composition for inhalation, which contains a compound represented by formula (I), a pharmacologically acceptable salt thereof, or a hydrate of the compound or the salt, as a medicinal ingredient. (In this connection, a compound represented by formula (II) may be contained in addition to the compound represented by formula (I).)