An engine includes, a cylinder head, an intake valve, an exhaust valve, and a first clearance adjusting mechanism for actuating the intake valve. The first clearance adjusting mechanism (1) maintains a first valve clearance when the intake valve and the cylinder head are in a cold state, such that the intake valve closes after a bottom dead center, and (2) maintains a second valve clearance, shorter than the first valve clearance, when a temperature of the intake valve is in a hot state and a temperature of the cylinder head is still in the cold state, after a cold start of the engine, such that an open timing of the intake valve is advanced and a close timing of the intake valve is retarded. The exhaust valve opens and closes at fixed predetermined timings regardless of a temperature of the exhaust valve and the cylinder head.