The present invention is intended to suppress, in an exhaust gas purification system for an internal combustion engine capable of mixing and combusting liquid fuel and compressed natural gas, an excessive rise in temperature of an exhaust gas purification device at the time when the exhaust gas purification device is caused to regenerate. In the exhaust gas purification system for an internal combustion engine according to the present invention, when the liquid fuel and the compressed natural gas are caused to mix and combust in the internal combustion engine at the time of regenerating the exhaust gas purification device, an amount of HC to be supplied to the exhaust gas purification device from an HC supply device is decreased in comparison with the time when only the liquid fuel is caused to combust in the internal combustion engine.