To provide a cooling device for an engine improving cooling nature of the engine by increasing heat radiation nature of engine oil stored in an crank case.

An engine main body 10 is formed out of a crank case 2, a cylinder 12 and a cylinder head 15. A chain chamber 30 as a storage space storing timing chain 29 wound around a drive side sprocket 27 fixed on a crankshaft 1 supported by the crank case 2 and a driven side sprocket 28 fixed on a camshaft 22 supported by the cylinder head 15 is formed in the engine main body 10, and a plurality of cooling fins 31 are provided on the engine main body projecting in the chain chamber 30. Heat of oil L passing through an inside of the chain chamber 30 is radiated to an outside from the cooling fins 31 and oil L is efficiently cooled until returning to a crank chamber 9.