The present invention relates to a glass fiber-reinforced composite material, an asphalt mixture using the same, and a manufacturing method thereof, the method comprising manufacturing, as a mixed structure, a bundle type fiber reinforcing material by coating, with a polypropylene resin: a powder fraction reinforcing material having a pellet or particle type glass fiber powder fraction, the glass fiber powder fraction having economical and outstanding physical properties; and several strands of glass fiber, and adding the same to a hot asphalt mixture, thereby capable of being injected in a plant construction site in a simple manner and improving the performance of the asphalt by preventing the phenomenon of the fiber being tangled within the produced hot asphalt mixture.