A muffler for a vehicle includes a plurality of baffles fixed at a predetermined distance in a longitudinal direction of a muffler housing, an exhaust gas inflow pipe, an intermediate pipe, and a plurality of exhaust gas outflow pipes having an inlet thereof positioned in the same chamber defined by the adjacent pair of the baffles with the outlet of the intermediate pipe to considerably reduce exhaust noise, flow-induced noise, and booming noise of exhaust gas. The muffler is effectively protected from thermal damage of a vehicle by implementing a sound-absorbing heat-insulating material therein, and impresses consumers with dynamic, powerful, and polished image by making the exhaust gas outflow pipe in a dual type composed of first and second exhaust gas outflow pipes and disposing the outlet at the lower center of a rear bumper to be exposed to the outside, thereby considerably improving productivity of vehicles.