A fuel supply control device for an internal combustion engine in which fuel is injected from a fuel injection device (6) in an intake port (2.1) and air that flows into the intake port is mixed with the injected fuel to be supplied to combustion chamber (1) is shown, in which there are provided an intake control valve (20, 30) having a heater (7.3, 7.4) in the intake port and being capable of opening and closing the mixed gas flow passage. Control circuits (12, 13) carry out opening and closing position control of the intake control valve (20, 30) so that, at least during the time when the heater (7.3, 7.4) generates heat, the portion of the heat-generating region of the intake control valve (20, 30) may be located in the fuel injection range, with the valve (20, 30) functioning as a variable heater, variable intake valve and an AD port.