In an antenna coil device 11, a coil portion 12 having a lead wire 2 wound around a magnetic core 1 is mounted on a case 3 made of plastic resin, and on one side of the case 3, terminal boards 4 and 5 that electrically connect one end and the other end of the lead wire 2 of the coil portion 12 to an external device are placed in a protruding manner. A through hole 4D is provided in an inserting end portion 4C of the terminal board 4, a through hole 5H is provided in a central flat portion 5G of the terminal board 5, and the two through holes 4D and 5H are placed opposite each other. This reduces stray capacitance caused between the two terminal boards 4 and 5 connected to both ends of the coil portion 12, and allows a self resonance frequency band where an impedance is equal to or above a predetermined value to be shifted to a high frequency side.