Abstract: A lock device includes a locking unit, a connecting unit, and a latch. The locking unit includes a shank, a rotation knob, a control wheel, a plurality of number wheels, a plurality of locating pieces, and a plurality of snap-fit members. The shank has a first positioning hole. The rotation knob has a second positioning hole combined with the first positioning hole of the shank by a positioning member. Thus, the user has to detach the positioning member from the first positioning hole of the shank to release the rotation knob so as to rotate the rotation knob for changing the code of the number wheels, thereby preventing the user from changing the code of the number wheels freely when rotating the rotation knob unintentionally.