This article shows a numerical simulation of the transverse cell in a H-2/O-2 diverging cylindrical detonation. An advection upstream splitting method with a diminishing variation scheme (AUSMDV scheme) and a detailed chemical kinetic model of H2/O2 by Petersen and Hanson were used to improve the numerical resolutions for fluid dynamics and for chemical kinetics, respectively. In the numerical results, the irregular cellular pattern and transverse cells were obtained by direct initiation. The numerical results indicated the detailed transverse detonation structure formed the complex Mach configuration, and sub-transverse waves on the transverse detonation were observed. These discussions suggest that the sub-transverse wave on thetransverse detonation destabilizes the cylindrical detonation front due to sub-transverse wave propagation toward the detonation front. This unstable factor from the sub-transverse wave develops the new transverse wave, which traces the fine cell, resulting in the appearance of cell bifurcation.