A reversible ratchet wrench without a switch knob has a handle portion and a head portion. The head portion has an accommodation trough, a detent trough, and a blind hole. A ratchet wheel is disposed in the accommodation trough and displaceable in the accommodation trough toward the handle portion to form a first position and a second position. A detent is disposed in the detent trough. Left and right sides of one surface of the detent are formed with push portions, respectively. An elastic member is disposed in the blind hole and pressed against one of the push portions. For a reverse switch, the ratchet wheel is displaced to the second position and then the ratchet wheel is turned, so that the elastic member is pressed against the other push portion.