A braking structure of a ratchet wrench comprises: a wrench head, having an operating portion, a rear end thereof being a head pivoting portion, a peripheral of the head pivoting portion having plural urging grooves; a wrench handle, a front end thereof having a handle pivoting portion pivotally connected with the head pivoting portion, the handle pivoting portion having a pivoting room, an acting through hole at a rear end of the pivoting room and extending toward the wrench handle, a positioning device being neighbor to a rear end of the handle pivoting portion and having a slim acting slot, a hole being in the acting slot and being perpendicular to an extension direction of the wrench handle; an urging device, having an urging rod; an operation device, having a pushing member that has an inserting rod, the inserting rod having a positioning through hole vertical to the inserting rod.