The metal jet that is flowed out by the oblique collision between a metal flier plate and a metal block becomes a high velocity. We have been developing the device that makes a material extremely high pressure by using the metal jet. The flier plate of the previous device had been accelerated by using a high explosive. There were several problems in the collection and analysis of the material that had been made the high pressure. Therefore we thought up the new device of which the flier plate was accelerated by a powder gun. The collision process was examined by a numerical simulation because the collision process of the flier plate of this device differs from that of the previous device. LS-DYNA was used for a numerical simulation and the difference of the collision process was clarified.