Isothermal-isobaric molecular dynamics simulations of molecular crystal SnI4 are carried out based on a model consisting of rigid tetrahedral molecules interacting via van der Waals forces. The hehavior of the crystal upon an increase in pressure is satisfactorily reproduced on both microscopic and macroscopic scales in the pressure regime in which the low-pressure phase is stable. In particular the compression curve obtained is in excellent agreement with the experimentally determined one. Upon further increase in pressure, however. no symmetry change is detected in the present simulations over the pressure regime in which the phase transformation and the subsequent solid state amorphization are experimentally found to take place.