An adjustable wrench has a wrench body, a clamping element and a ratcheting jaw. The wrench body has a handle, a head and a thumbscrew. The head is formed on a front end of the handle and has a connecting block, a fixed jaw, a curved slot, a positioning pin, a mounting recess and a sliding slot. The clamping element is movably connected to the wrench body and has a rear end, a front end, a sliding bar and a movable jaw. The sliding bar is formed on the rear end of the clamping element, is mounted in the sliding slot and engages the thumbscrew and has multiple teeth. The ratcheting jaw is a curved block capable of sliding forward and retracting backward inside the curved slot and has a backward area, a forward area, a guide hole, an engaging surface, an abutting surface, an engaging protrusion and a spring.