A semiconductor module includes a substrate having a central region, an outer region that surrounds the central region, and a middle region disposed between the central and the outer region, a first semiconductor package mounted on the central region of the substrate, a plurality of second semiconductor packages mounted on the middle region of the substrate, and a heat radiation structure disposed on the first semiconductor package and second semiconductor packages. The heat radiation structure includes a first part that is disposed on top surfaces of the first and second semiconductor packages, a second part that surrounds the middle region, a third part that is spaced apart from the second part and surrounds the first semiconductor package, and a fourth part that connects the second part to the third part.