The numerical simulations on the train entering a tunnel are performed by solving unsteady axi-symmetric problems. To reduce the effects of the pressure wave generated by the train starting abruptly, several starting methods of the train are examined. The high order velocity increase gives better results than those for the linear velocity increase. The high order velocity increase gives good results for the pressure rise by the train entering a tunnel, too. The distance to the train reaches the highest running velocity from the start should be more than 60 m when the train speed is 350 km/h.