A regeneration controller for preventing particulate matter from increasing when an exhaust purification apparatus is inactivated. The regeneration controller includes an ECU 70 for heating the exhaust purification apparatus and eliminating the particulate matter accumulated in the exhaust purification apparatus when an estimated accumulation amount is greater than a reference accumulation amount. The ECU 70 obtains the estimated accumulation amount by estimating the amount of particulate matter accumulated in the exhaust purification apparatus. An exhaust temperature sensor 44 detects the temperature of the exhaust purification apparatus. The ECU 70 intermittently decreases the air-fuel ratio of exhaust to heat the exhaust purification apparatus and perform burn-up heating for burning the particulate matter. The ECU 70 further prohibits burn-up heating when the temperature detected by an exhaust temperature sensor 44 decreases to a catalyst inactivation level.