According to an ignition device, a first switching unit applies a voltage between electrodes of by spark plug by turning on/off energization from an on-vehicle battery to a primary coil. Further, a second switching unit applies a voltage having the same direction as a spark discharge generated by turning on/off the first switching unit between the electrodes of the spark plug by supplying electrical energy accumulated in a booster circuit into a primary coil. Accordingly, it is possible to greatly reduce a complexity of the on/off switching of the first and second switching units compared to a conventional technology.