To provide an internal combustion engine equipped with protective covers for an air cleaner and a carburetor, which are improved in their defective molding, increased in their strength and improved in their appearance design.

An engine 10 has an engine body 14, an intake-side protective cover 15 which is disposed on the engine body 14 at the intake side and is provided on its outer surface with recessed outer-surface grooves 15e, and an exhaust-side protective cover 16 which is disposed at the opposite side to the intake-side protective cover 15 with respect to the engine body 14 as the center. The outer-surface grooves 15e in the intake-side protective cover 15 have the same width and intervals as an appropriate number of parallel, slit-like radiating through holes 16e recessed in the exhaust-side protective cover 16.