An ECU outputs an ignition signal and a discharge waveform control signal. An ignition device performs a closing operation of an ignition switching device while the ignition signal is input into the ignition device. The ignition device adjusts a current flowing through a primary coil to a discharge current command value determined based on the discharge waveform control signal, by performing an opening-closing operation of a control switching device in a period in which the discharge waveform control signal is input into the ignition device after an input of the ignition signal into the ignition device is stopped. The ECU sets the discharge current command value that is a command value for a discharge current of a spark plug to a higher value as a rotation speed is higher, and prolongs a duration, in which discharge controller controls the discharge current, as the rotation speed is lower.

An ECU outputs an ignition signal and a discharge waveform control signal. An ignition device performs a closing operation of an ignition switching device while the ignition signal is input into the ignition device. The ignition device adjusts a current flowing through a primary coil to a discharge current command value determined based on the discharge waveform control signal, by performing an opening-closing operation of a control switching device in a period in which the discharge waveform control signal is input into the ignition device after an input of the ignition signal into the ignition device is stopped. The ECU sets the discharge current command value that is a command value for a discharge current of a spark plug to a higher value as a rotation speed is higher, and prolongs a duration, in which discharge controller controls the discharge current, as the rotation speed is lower.

When an abnormality judgement section judges that there is a failure of an energy inputting circuit, an energy inputting line, through which electrical energy is inputted from the energy inputting circuit to a primary winding, is changed over to a disconnected state by output halt switching means. As a result, since inputting of electrical energy to the primary winding is thereby halted, problems arising due to continuation of inputting electrical energy to the energy inputting circuit can be prevented, even in the event of a failure of the energy inputting circuit, so that reliability can be enhanced.

When an abnormality judgement section judges that there is a failure of an energy inputting circuit, an energy inputting line, through which electrical energy is inputted from the energy inputting circuit to a primary winding, is changed over to a disconnected state by output halt switching means. As a result, since inputting of electrical energy to the primary winding is thereby halted, problems arising due to continuation of inputting electrical energy to the energy inputting circuit can be prevented, even in the event of a failure of the energy inputting circuit, so that reliability can be enhanced.

An ignition apparatus inputs energy during a predetermined energy input period after the interruption of a primary electric current by an ignition switch and a discharge of an ignition plug caused by a secondary electric current. Moreover, the ignition apparatus includes a blow-off detection unit that detects, during the energy input period IGW after the start of the discharge by the ignition plug, occurrence of blow-off of the discharge. When the secondary electric current I2 drops below a blow-off detection electric current threshold value Ibo at a time instant tbo in a second region where it is impossible to perform a re-discharge after blow-off, the blow-off detection unit determines that blow-off has occurred and the ignition apparatus stops the energy input from an energy input unit to an ignition coil. By preventing unnecessary energy input, it is possible to suppress unnecessary electric power consumption and wear of electrodes of the ignition plug.

An ignition device includes a secondary current control circuit that receives a secondary current control signal IGa from an ECU, and a feedback circuit outputs a control signal for controlling energization of an primary coil to an energy supply circuit according to a result of comparison of a control value of the secondary current outputted from the secondary current control circuit and a detected value of the secondary current. Further, the ECU outputs a secondary current control signal IGa in accordance with engine parameters. Thereby, the secondary current substantially indicating the amount of energy that is supplied into the ignition coil from the energy supply circuit can be controlled in accordance with the operating condition of the engine. Therefore, it is possible to suppress excess or shortage of energy supplied from the energy supply circuit to an ignition coil from occurring.

An ECU outputs an ignition signal and a discharge waveform control signal. An ignition device closes an ignition switching element in a period during which the ignition signal is input. After a stop of the input of the ignition signal and in a period of input of the discharge waveform control signal, the ignition device controls current flowing through a primary coil to a discharge current command value that is determined by the discharge waveform control signal by opening or closing a control switching element. A discharge control unit determines whether there is an abnormality. When it is determined that there is an abnormality, the ECU avoids control executed by the discharge control unit, and causes the discharge control unit to execute control during times of low-rotation and low-load operation of an internal combustion engine in order to determine whether the discharge control unit has returned to a normal state.