In an apparatus for controlling operation of two outboard motors mounted on a stern of a boat side by side and each equipped with an internal combustion engine to power a propeller through a power transmission shaft and a transmission having a forward first-speed and a second-speed gear and a reverse gear supported on the power transmission shaft, control is conducted at turning of the boat to operate the inner one of the outboard motors to transmit the engine power to the propeller through the reverse gear, and to operate the outer one of the outboard motors to transmit the engine power to the propeller through the forward first-speed gear, when the detected engine speed is equal to or smaller than a predetermined first speed and the detected rudder angle is equal to or greater than a predetermined angle.