As electronic devices become highly integrated, more heat is generated, and this heat not only degrades the function of the device, but also causes malfunction of peripheral devices, so much interest and research are being made on technology for controlling heat. Heat radiating materials are mainly manufactured in a composite form by adding a thermally conductive filler to a polymer. And in order to achieve high thermal conductivity, the amount of filler must be increased, which makes processing difficult and the mechanical properties of the composite material deteriorate. In this study, a new filler encapsulating paraffin is introduced to increase the heat dissipation effect of the heat radiating material. Paraffin undergoes a phase change to a liquid due to heat, and a liquid leak of paraffin occurs in the heat dissipating material, acting as a defect. Accordingly, the leakage problem was solved by encapsulating paraffin using polyurethane as a wall material. Paraffin microencapsules were not homogeneous, but formed particles with a diameter of about 100 μm. In addition, as a result of measuring the thermal conductivity of the prepared epoxy/(paraffin microencapsule+alumina) heat radiating material, it was confirmed that thermal conductivity gradually decreased due to the introduction of paraffin microencapsules, resulting in continuous heat dissipation.