Internal combustion engine apparatus, control method thereof, and vehicle

When a misfire occurs in any cylinder of an engine, an exhaust switching valve is closed to pass exhaust gas through an HC adsorbing section to a catalytic purifying section having a three-way catalyst (step S). Thus, unburned fuel (HC) mixed in the exhaust gas due to a misfire of the engine can be adsorbed in the HC adsorbing section. Accordingly, unburned fuel (HC) due to a misfire after the start of the engine is completed can be prevented from being exhausted.