A dumbbell with adjustable weight essentially includes a handle, two first weight blocks, two second weight blocks, and two position-limiting elements. The handle has a gripping portion and two arms protruding outward from the gripping portion. The first weight blocks are removably disposed around the arms of the handle, respectively. The second weight blocks are removably disposed around the first weight blocks, respectively. The position-limiting elements abut against the second weight blocks ends, respectively. Hence, a user can adjust the total weight of the dumbbell by changing or removing the second weight blocks.