Prediction of light scattering is required to develop the optical measuring techniques for detecting the size and shape of an individual non-spherical particle. However, the applicability of well- known Lorentz-Mie theory is fairly limited and is unsuitable for this purpose. In this paper, we examine the feasibility of a direct solution method of Maxwell's electromagnetic wave equation for predicting the laser light scattering by a non-spherical object. It is confirmed that the Cartesian coordinate system is available for predicting light scattering, even if the shape of a scattering object is stepwise approximated based on the Cartesian coordinate system. That is, a complex coordinate system matched to the shape of a scattering object is not required. In addition, it is clarified that the electromagnetic field produced in the near field of a scattering object remarkably varies depending on its cross sectional shape even if the scattering patterns are almost same in the backward far field. This suggests that the estimation of multiple scattering effects in the optical particle sizing techniques should be conducted based on the near field scattering pattern. The method employed in this paper is suitable also for these purposes because this method can easily deal with a closely allocated group of scattering objects.