This utility model relates to the field of dumbbells and, in particular, to an adjustable dumbbell comprising knobs, bridge-shaped blocks, weight plates, a lift assembly, side plates, an anti-slip assembly and sleeves. The number of the weight plates is two, and they are fixedly attached to the opposing ends of the lift assembly. The bridge-shaped blocks and the weight plates are fixedly disposed between the lift assembly and the knobs. Separation of sockets from inserting plates concurs with extraction of a securing bar from a second through hole and from a first through hole. The handle may be then pulled to a desired position by virtue of the movement of locking blocks in respective locking grooves.