Control apparatus for engine

A first calculation device (6) is provided that calculates a ratio of a target torque equivalent value of an engine to a maximum torque equivalent value of the engine, as a pressure ratio equivalent value. A second calculation device (7) is also provided that calculates a flow velocity of air to flowing through a throttle valve in the engine, based on the pressure ratio equivalent value calculated by the first calculation device (6) . A third calculation device (8) is further provided that calculates a target throttle valve opening, based on the flow velocity calculated by the second calculation device (7). With this configuration, the target opening of a throttle valve (27) corresponding to the requested engine torque, without using the pressures before and after the throttle valve section.