A ratchet wrench includes a wrench body having a circular space defined at a head portion of the wrench body, a ratchet with a hollow center placed into the circular space. The ratchet is symmetric to the wrench body. The inner wall of the ratchet has a plurality of first ridges formed thereon. A first recess is formed between each of two adjacent first ridges. Each of the first recesses selectively has a second ridge formed thereon. A second recess is defined on the second ridge. The shape of the second recess is as same as the first recess. In this way, a user can directly alternate the big and small bolts in the ratchet wrench, rather than turn over the wrench to fit the big or small bolt.