A memory module includes a first redistribution structure, a second redistribution structure, first semiconductor dies, second semiconductor dies, an encapsulant, through insulator vias and thermally conductive material. Second redistribution structure is stacked over first redistribution structure. First semiconductor dies are sandwiched between first redistribution structure and second redistribution structure and disposed side by side. Second semiconductor dies are disposed on the second redistribution structure. The encapsulant laterally wraps the second semiconductor dies. The through insulator vias are disposed among the first semiconductor dies, extending from the first redistribution structure to the second redistribution structure. The through insulator vias are electrically connected to the first redistribution structure and the second redistribution structure. The thermally conductive material is disposed on the second redistribution structure, among the second semiconductor dies and overlying the through insulator vias. The thermally conductive material has a thermal conductivity larger than that of the encapsulant.