An RFID tag with an RFIC module including a substrate, an RFIC chip disposed on the substrate, and a loop conductor disposed on the substrate and connected to the RFIC chip; and an antenna base material mounted with the RFIC module and including an antenna conductor with a radiating portion radiating radio waves and a coupling portion connected to the radiating portion, for electromagnetic field coupling with the loop conductor. Moreover, the loop conductor includes a first loop pattern formed on a first main surface of the substrate, a second loop pattern formed on a second main surface confronting the first main surface, and an interlayer connection conductor extending through the substrate, for connecting the first and the second loop patterns in series.