An exhaust system for an internal combustion engine, configured to enhance a silencing effect while being miniaturized. The exhaust system includes a muffler body configured in such a manner that a first expansion chamber and a second expansion chamber separated from each other are partitioned therein. A plurality of exhaust pipes extend from an internal combustion engine and are connected to the first expansion chamber. A communication pipe is configured to be connected to the first expansion chamber and the second expansion chamber, to merge exhaust gas from the plurality of exhaust pipes, and to introduce the merged exhaust gas into the second expansion chamber.