An intake charge regulating apparatus for an engine includes a throttle body having a throttle bore formed therein for communicating with an intake port, and a throttle valve for controlling flow through the throttle bore. A throttle-driving mechanism includes an electric motor and a transmission mechanism for decelerating a driving force of the electric motor and for transmitting the driving force to the throttle valve. A camshaft sprocket is fixed to an end portion of a camshaft, which is included in a valve train for driving intake and exhaust valves in a cylinder head to open and close. The throttle-driving mechanism is arranged opposite a side where the camshaft sprocket is located in an axis direction of the crankshaft. The electric motor is disposed between the throttle body and the cylinder head in top plan view.