An ignition apparatus of an engine includes a spark plug disposed in a combustion chamber, and configured to generate a spark discharge between a center electrode and a ground electrode, a plurality of ignition coils each applying a current to the spark plug and including a primary coil, a secondary coil, a main switch, and an auxiliary switch, and a controller selectively performing a multi-stage ignition through a first ignition coil and a second ignition coil or a single-stage ignition through one ignition coil among the first ignition coil and the second ignition coil, adjusting a charging speed, a number of discharges, and a discharge maintaining period of the ignition coil depending on a driving point of the engine, and adjusting the charging speed of the ignition coil and a target air/fuel ratio for performing a lean combustion, based on a state of charge of a battery.