An antenna coil housed in a tubular case has a holder made from resin, which is fitted on a magnetic-material core. This holder has a core holding part, which holds the magnetic-material core, and a lead wire holding part, which holds lead wires. The lead wire holding part has first holding parts 22a, which hold the lead wires in the X direction, near the ends, and second holding parts 22b, which hold the ends of the lead wires in the Y direction, the ends of the coil being connected to conductors of the lead wires, which are led out via the second holding parts 22b.