An adjustable wrench includes a fixed jaw, a movable jaw, and a handle. The fixed jaw includes a chamber and a hole defined therein. An adjusting mechanism and an abutting mechanism are disposed in the chamber. The adjusting mechanism includes a worm gear and a fixing member. The abutting mechanism includes an abutting member. The handle is pivotally fixed to the fixed jaw. The adjustable wrench is operable in a first direction wrenching an object and includes the worm gear stopped from moving along the fixing member by the abutting member fixedly abutting against the worm gear. The adjustable wrench is operable in a second direction moving relative to the object and includes the worm gear adapted to be moved with respect to the fixing member and including the movable jaw moving with respect to the fixed jaw and the abutting member not fixedly abutted against the worm gear.