Melting transition of polyethylene crystals was studied by light-modulated calorimetry. The light-modulated calorimeter (or light-heating dynamic DSC) was constructed using heating through light to give heat-how modulation to the sample. Frequency dependence of the complex heat capacity was measured in the (0.01-0.2) Hz range. It was found that, in the melting-temperatures range, the real part of the complex heat capacity at frequencies equal to or higher than 0.1 Hz reached limiting value at a sufficiently high frequency. Linearity between the cyclic temperature change of the sample and the modulation, and the difference between melting and crystallization from the viewpoint of the complex heat capacity were also investigated.