We have simulated the rupture process of the 1992 Landers, California, earthquake using a realistic nonplanar fault geometry, including fault bends and branches, through a three-dimensional boundary integral equation method. Considering an external loading system due to local tectonics as well as a nonplanar fault structure, we could reproduce the characteristic features of this earthquake such as spontaneous rupture transfer between faults, pattern of slip distribution, and propagation of rupture front without assuming any laterally heterogeneous distribution of parameters. We could also reproduce seismic waveforms near the faults, especially in the forward direction of rupture propagation, where rupture directivity controlled by rupture transfer between faults significantly affects ground motion.