To provide an ignition switch device for shortly setting a key part of an ignition key while providing an antenna for receiving an ID code transmitted from a transponder.

This ignition switch device includes a cylinder body 1 forming a key hole 2a and making a rotationally operable rotor 2 exist inside by insertion of the key part Ikb of the ignition key IK into the key hole 2a and the antenna 6 capable of receiving the ID code transmitted from the transponder T formed in a gripping part IKa of the ignition key IK, and permits starting of an engine on condition of discriminating that the ID code received by the antenna 6 is predetermined and normal. The antenna 6 is arranged in a side position of the rotor 2 and in a position under an insertion port P of the key part IKb of the ignition key IK.