In an RFID tag mounting package mounted with an RFID tag and a manufacturing method thereof, in order to have sufficient communication performance without spoiling the design property of the package to which a conductive film is applied, a package is obtained by assembling a structural material in which a metallic film is formed on a base material made of paper or the like. In the package, a slot is provided in the metallic film of a folded portion, in a spot where portions (the folded portion and an external packaging portion) of the structural material overlap each other. An inlet operates as an RFID tag, includes an antenna and an IC chip connected to the antenna, and is mounted on the inner surface of the folded portion in conformity with the position of the slot.