To provide an ignition device at a low cost with high reliability of durability provided with a current detection means on a primary coil side not requiring a high voltage resistance component.

On the primary coil 51 side of an ignition coil 5, a closed loop circuit 25 connecting a thyristor 23 and a current detection section 6 in series is constructed. After application of an igniting high voltage Vd on an ignition plug 9 for generating spark discharge, the closed loop circuit 25 is closed with the gate signal Vb of the thyristor 23 as H, and then, a current Ib is passed through the closed loop circuit 25. The current detection section 6 detects the current Ib, converts the current into a voltage, and inputs it in an ECU 8 as a voltage value Vc. This voltage value Vc is varied according to a dielectric breakdown voltage value between the central electrode 91 and grounding electrode of the ignition plug 9, and is usable for detection of abnormality.