An exhaust gas purification apparatus for an internal combustion engine is designed to prevent a decrease in the accuracy of measurement by a PM sensor (17). The apparatus includes an NOx catalyst (7) provided in an exhaust passage (3) of an internal combustion engine (1) to reduce NOx by reducing agent supplied to it, a supplying device (6) that supplies urea to the NOx catalyst (7) from the upstream of the NOx catalyst (7), the PM sensor (17) that detects the amount of particulate matter in the exhaust gas in the downstream of the NOx catalyst (7), and a restriction part (10) that restricts supply of urea by the supplying device (6) when the amount of particulate matter adhering to the NOx catalyst (7) is equal to or larger than a threshold.