An ignition apparatus which allows for an accurate diagnosis of a spark plug in an internal combustion engine provided with plural spark plugs for each cylinder is provided for an internal combustion engine. The ignition apparatus is for an internal combustion engine provided with plural spark plugs for each cylinder, and includes an input port which receives fail signals S3 and S4 generated corresponding to each of the plural spark plugs for diagnosis of the spark plugs. An input timing of the fail signal to the input port is made different for each of the plural fail signals. Ignition timings S1, S2 of the plural spark plugs are set to different times.