To provide a coil device in which coils can be arranged without using a circulation coil and without cutting a conveyor belt, and its manufacturing method regarding the coil device used for an RFID system, and to provide its manufacturing method.

The coil device is provided with a tubular housing provided so as to surround the conveyor belt of an endless conveying path for carrying objects such as cargoes and mails on its upper face. In the coil device, the tubular housing comprises a first member arranged on one side of the conveyor belt and a second member arranged on the other side of the conveyor belt, a first coil and a second coil are provided on the first member, a third coil and a fourth coil are provided on the second member, and a fifth coil and a sixth coil are respectively provided on two face parts formed by the first member and the second member.