We simulated spontaneous rupture processes on a vertical, bending strike slip fault in a three-dimensional half space, using a finite-difference method. Rupture area and overall slip distribution on the fault vary with the initial stress field, which depends on strike change at the bend. Rupture velocity and detailed slip distribution around the bend, on the other hand, are affected by time-dependent normal stress change caused by rupture. This dynamic stress change plays an important role in the rupture process ahead of the bend, as well as in the resulting ground motion. The numerical simulation method demonstrated here in a simplified geometry is equally applicable to modeling strong ground motion from geometrically complex ruptures in realistic earth models.