A semiconductor package includes: a first package substrate; a first semiconductor device mounted on the first package substrate; a second package substrate arranged on an upper part of the first semiconductor device; and a heat-dissipating material layer arranged between the first semiconductor device and the second package substrate and having a thermal conductivity of approximately 0.5 W/m·K to approximately 20 W/m·K, wherein the heat-dissipating material layer is in direct contact with an upper surface of the first semiconductor device and a conductor of the second package substrate.