In the method of manufacturing an IC module (1) including a resin packaging process using upper and lower dies (5) for forming a cavity (50) while the dies are clamped, the resin packaging process is carried out by introducing a melted resin while a substrate (2) on which an IC chip (3) is placed and a coil (20A) which has a doughnut shape when observed from above and is flattened as a whole are housed in the cavity (50). When a substrate (2) on which an antenna coil (20) is patterned is to be packaged with a resin, the resin packaging process is carried out by forming a spacer (28) having an equal and almost equal height to the height of the cavity (50) on the substrate (2), housing it in the cavity (50), and introducing a melted resin. Instead of forming the spacer (28) on the substrate (2), a substrate (2) housed in a cavity (50) may be sucked. The manufacturing method can provide good protection of an IC chip and an antenna coil.