A ratchet wrench has a handle, a transmitting device, a torque adjusting device and a ratchet head. The transmitting device is connected to the handle and has a barrel, a transmitting seat and a transmitting shaft. The barrel is connected to the handle and has two threaded segments and multiple elongated holes. The transmitting shaft is rotatably mounted in the barrel and has a driving disk and an eccentric rod. The torque adjusting device is connected to the transmitting device and has a casing, a limiting assembly and a spring. The casing is connected to the barrel. The limiting assembly is mounted around the transmitting shaft and has two pressing rings and a push bearing. The spring is mounted around the transmitting shaft and presses against the pressing rings to push the holding pins abutting with the holding recess. The ratchet head is connected to the transmitting device.