A ratchet wrench includes a wrench body having a drive head formed with a receiving recess, a ratchet wheel rotatably mounted in the receiving recess of the drive head, a positioning member secured in the receiving recess of the drive head and secured on the ratchet wheel to retain the ratchet wheel in the receiving recess of the drive head, and an oil seal secured in the receiving recess of the drive head and enclosed around the positioning member. Thus, the positioning member is a C-shaped snap that can abut and press the oil seal so as to position the oil seal actually, so that the oil seal has a better positioning effect.