A combiner-positioning apparatus for a vehicular head-up display is provided. The combiner-positioning apparatus includes a drive unit for supplying a driving force, a combiner assembly including a combiner, the combiner being projected and exposed to an outside or retracted or hidden into a slot formed in a dashboard by the driving force, a guide unit for guiding sliding movement of the combiner assembly in a vertical direction, and a power transmitter for transmitting the driving force to the combiner assembly.