A controlling apparatus for an engine includes a purge path connected to a sealing-type fuel tank and an intake system of an engine and is configured to allow purge gas containing evaporated fuel from the fuel tank to flow therethrough. A purge valve placed in the purge path is configured to adjust a flow rate of the purge gas. A calculation unit calculates a degree of opening of the purge valve based on a target introduction ratio of the purge gas, and a controlling unit controls the purge valve so as to establish the degree of opening calculated by the calculation unit. The calculation unit corrects, in high-pressure purge performed when a pressure in the fuel tank increases exceeding a predetermined pressure, the degree of opening using a tank pressure flow velocity correction coefficient K2 corresponding to an upstream pressure of the purge valve.