A ratchet wrench includes a wrench body, a ratchet wheel, a cover, and a positioning device mounted between the cover and the wrench body. The positioning device includes a locking plate, a push plate, and an elastic plate. Thus, the locking portion of the locking plate is extended into the through hole of the cover and detachably locked in the annular groove of the socket to lock the socket on the cover, so that the socket is positioned on the wrench body rigidly and stably without detachment, thereby facilitating a user operating the wrench body and the socket to rotate a workpiece, such as a nut, bolt or the like.