A controller of an engine that can use a blended fuel with alcohol blended therein, the controller includes: an ignition timing controller, operable to control an ignition timing of the engine; an exhaust air-fuel ratio detector, operable to detect an exhaust air-fuel ratio of the engine; a concentration detector, operable to detect concentration of the alcohol in the blended fuel; an operation state detector, operable to detect an operation state of the engine; and a corrector, when the operation state which is detected by the operation state detector is a high-speed, high-load operation state, as the concentration of the alcohol which is detected by the concentration detector is higher, operable to control an injection amount which is injected from a fuel injection valve to correct a target equivalence ratio more in a lean direction, and operable to correct the ignition timing which is controlled by the ignition timing controller more to a spark advance side.