The present invention relates to a thermosetting resin composition, for a semiconductor package, having excellent flowability and stiffness, and a prepreg using same. More particularly, provided are a thermosetting resin composition for a semiconductor package, a prepreg using same, and a metal foil laminate including the prepreg, wherein the composition includes three specific fillers having different average particle diameters in a binder resin system containing epoxy resin, bismaleimide resin, diaminodiphenyl sulfone resin, and benzoxazine resin, thereby being able to ensure excellent flowability and stiffness even when the amount of filler is higher than that of the prior art, and to contribute to the driving properties of a slim electronic device.