A combiner-positioning apparatus for a vehicular head-up display, the combiner-positioning apparatus comprising: 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 having a movement guide rail (310a, 310b, 320a, 320b) for guiding sliding movement of the combiner assembly in a vertical direction; a power transmission unit for transmitting the driving force to the combiner assembly; wherein: the combiner assembly comprises: a lifting module vertically movable by the driving force transmitted via the power transmission unit; and a holder connected to the lifting module and including a combiner-moving boss (231a, 231b), the combiner-moving boss (231a, 231b) being slidably moved along the movement guide rail (310a, 310b, 320a, 320b) while the combiner is held, characterized in that the combiner-positioning apparatus comprises a slot cover configured to open and close the slot; and in that the combiner-positioning apparatus further comprises a lever (610a, 610b), the lever (610a, 610b) having a first end connected to the slot cover and a second end connected to the combiner-moving boss (231a, 231b), the lever (610a, 610b) is rotatable about a rotational shaft between the first end and the second end according to the movement of the lifting module, and the slot cover opens or closes the slot according to the rotation of the lever (610a, 610b). 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 having a movement guide rail (310a, 310b, 320a, 320b) for guiding sliding movement of the combiner assembly in a vertical direction; a power transmission unit for transmitting the driving force to the combiner assembly; wherein: the combiner assembly comprises: a lifting module vertically movable by the driving force transmitted via the power transmission unit; and a holder connected to the lifting module and including a combiner-moving boss (231a, 231b), the combiner-moving boss (231a, 231b) being slidably moved along the movement guide rail (310a, 310b, 320a, 320b) while the combiner is held, characterized in that the combiner-positioning apparatus comprises a slot cover configured to open and close the slot; and in that the combiner-positioning apparatus further comprises a lever (610a, 610b), the lever (610a, 610b) having a first end connected to the slot cover and a second end connected to the combiner-moving boss (231a, 231b), the lever (610a, 610b) is rotatable about a rotational shaft between the first end and the second end according to the movement of the lifting module, and the slot cover opens or closes the slot according to the rotation of the lever (610a, 610b). a lifting module vertically movable by the driving force transmitted via the power transmission unit; and a holder connected to the lifting module and including a combiner-moving boss (231a, 231b), the combiner-moving boss (231a, 231b) being slidably moved along the movement guide rail (310a, 310b, 320a, 320b) while the combiner is held, characterized in that the combiner-positioning apparatus comprises a slot cover configured to open and close the slot; and in that the combiner-positioning apparatus further comprises a lever (610a, 610b), the lever (610a, 610b) having a first end connected to the slot cover and a second end connected to the combiner-moving boss (231a, 231b), the lever (610a, 610b) is rotatable about a rotational shaft between the first end and the second end according to the movement of the lifting module, and the slot cover opens or closes the slot according to the rotation of the lever (610a, 610b).