An adjustable wrench includes a frame and a movable jaw. The frame includes a handle, a fixed jaw, a guiding slot formed between the handle and the fixed jaw, a hole communicated with the guiding slot, and a holding portion. An adjusting screw is rotatably engaged in the hole. The movable jaw includes a guiding portion slidably engaged in the guiding slot, a supporting portion formed at a bottom side of the guiding portion, and an adjusting portion formed at a top side of the guiding portion. The supporting portion is abutted against the holding portion. The adjusting portion is engaged with the adjusting screw.