In recent years, periodic photonic crystal structures have attracted much attention due to potential application in controlling electromagnetic wave propagation [1]. In this paper, the photonic band gaps in two-dimensional photonic crystal with square lattice composed of half-elliptical rods in air are studied using the plane-wave expansion method. The refractive index of the rods is n = 3.47. In order to analyze the effects of the above-mentioned rod structure on photonic band gaps, we vary the ellipticity. The obtained results are compared with calculations for circular and elliptical rods with the same filling factor. It is observed that the size of the photonic band gap changes with changing ellipticity of the constituent rods and it is bigger than in the case of circular and elliptical rods. These results were obtained using the OptiFDTD 8.0.0.428 software.