To provide a door lock, the mechanism of which is arranged so that an impact sound can be reduced by using one member constituting the door lock, without the installation of a special member, so as to reduce the impact sound generated on completion of an operation of a dead bolt.

In unlocking, a dead bolt unit is not damped and stopped by directly abutting on a wall surface of a chassis and the like but damped and stopped by the abutment of a dead spring retainer as a small-volume member. In abutment, the motion of the dead bolt unit is damped by a damping member such as a dead spring. The dead spring, which acts on a mechanism for preventing the abnormal operation and motion of the dead bolt, is also used as the damping member. Preferably, a resin material and the like are used for the dead spring retainer so that the impact sound can be reduced. Additionally, the dead spring retainer is protruded from a wall surface at the base of the dead bolt unit.