A computer code was developed for simulation of dislocation density in a bulk single crystal during the Czochralski growth process. In this computer code, the effects of crystal anisotropy such as the elastic constants and slip directions were approximately taken into account by averaging the Young's modulus, the Poisson's ratio and the resolved shear stress along the azimuthal direction. Axisymmetric finite element analysis can be applied to quantitative estimation of dislocation density during single crystal growth process by using such averaging technique together with the Haasen-Alexander-Sumino model as a creep constitutive equation of a single crystal at elevated temperatures. Dislocation density analyses were performed for both the [0 0 1] and [1 1 1] growth directions of a GaAs bulk single crystal. As a result, although the [1 1 1] growth direction has the larger average Young's modulus than the [0 0 1] growth direction, the former gives lower dislocation density than the latter.