A regeneration controller for an exhaust purification apparatus (36, 38) of an engine (2) that appropriately burns particulate matter accumulated in the exhaust purification apparatus. The regeneration controller includes an ECU (70) that determines whether an estimated accumulation amount (PMsm) of particulate matter deviates from an actual accumulation amount. When the estimated accumulation amount is less than or equal to a maximum value (BUpm) and an exhaust pressure difference (&Dgr;P/GA) is greater than a replacement reference value (Dp), the ECU replaces the estimated accumulation amount with a greater replacement amount (UPpm). This causes the estimated accumulation amount to approach or to be the same as the actual accumulation amount.