ENGINE CONTROLLER

A controller (1) of an engine performing a premixed combustion operation and a diffusion combustion operation that are switchable in accordance with the traveling state of a vehicle, includes a detector (2) detecting a sudden-deceleration request for sudden deceleration of the vehicle, on the basis of a driving operation from a driver, and a determiner (7) forbidding the premixed combustion operation and permitting the diffusion combustion operation during detection of the sudden-deceleration request at the detector (2).