To provide an ignition timing control device for an internal combustion engine that can suppress deterioration of an engine output, while suppressing knocking occurrence.

In the internal combustion engine 10, a blended fuel, where an alcohol fuel and a gasoline fuel are blended at an arbitrary ratio, is used. The control device 22 corrects a retarded ignition timing according to an intake temperature. When an alcohol concentration of the blended fuel is not lower than a predetermined value, the control unit 22 prohibits the correction of the retarded ignition timing according to the intake temperature.