Disclosed is an arrowhead in which a plurality of expandable blades can be quickly and reliably retracted or expanded without using an additional means to bundle the expanding blades, thereby enhancing the penetrating capability or killing capability of an arrow. Particularly, a portion of a shaft forming the arrowhead is provided with a rack gear portion installed thereon and a lower end of each of the expanding blades is provided with a pinion gear portion, such that the rack gear portion and the pinion gear portion engage with each other and such a rack-pinion action controls the operation of retracting or expanding the expanding blades.