EXHAUST PURIFICATION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

An exhaust gas purification system for an internal combustion engine, the system being provided with: an exhaust gas purification device (13) that is provided in an exhaust gas passage (12) of the internal combustion engine (1); a preceding stage catalyst (14) that is provided in the exhaust gas passage (12) at an upstream side of the exhaust gas purification device (13) and passed through by a part of exhaust gas that flows through the exhaust gas passage (12); a bypass passage (31) that directly introduces exhaust gas of the internal combustion engine (1) into the exhaust gas passage (12) at a downstream side of the preceding stage catalyst (14); and a bypass valve (34) that opens/closes the bypass passage (31).