There is provided an output voltage control apparatus for a vehicular AC generator in which a generator output voltage including a ripple component can be made to more approach a reference voltage. The control apparatus includes a comparison circuit to compare a detection voltage including a ripple component with a reference voltage and to output an effective comparison output in each of low output sections in which the detection voltage is lower than the reference voltage by the ripple component, an on period counter to count up, in a count enable period set in each of the control periods, a count value while adding the count value in each of the low output sections based on the effective comparison output, and a memory circuit to store a final count value in the count enable period in each of the control periods.