In detecting the occurrence of an abnormality in a variable valve timing mechanism, which continuously changes a valve timing by advancing or delaying the displacement angle of an intake-side cam shaft with respect to a crankshaft, an abnormality detecting apparatus for a valve timing control apparatus determines that the variable valve timing mechanism is failing when the absolute value of the difference between a target displacement angle and a correct real displacement angle, obtained by subtracting the maximum delay-angle learning value from the real displacement angle, is greater than a first predetermined value and the absolute value of the difference between a correct real displacement angle and a previous correct real displacement angle is equal to or smaller than a second predetermined value.