To provide a coil antenna and manufacturing method thereof capable of suppressing shape deformation of the coil antenna embedded in a non-vulcanized rubber.

A coil antenna 12 is formed by spirally winding a metal wire 12m in such a way that an angle formed between a winding direction and an axial direction of a coil to be formed becomes 70 or more, this is connected with a communicator 11c in a device body 11 of a pressure monitoring device 10 that is produced separately, and this is then set into a molding die and molded to produce a non-vulcanized cover rubber 13 in which the device body 11, to which the coil antenna 12 is connected, is embedded internally. The non-vulcanized rubber 13 in which the coil antenna 12 and the device body 11 are embedded is vulcanized to produce an electronic apparatus (pressure monitoring device 10) with the coil antenna covered with a rubber member.