A door latch actuator comprising: a reversible motor; a rotating object rotated by the motor normally and reversely; a drive portion rotated normally and reversely together with the rotating object; and an actuating member that moves from a lock position in which a locking mechanism of a door is in a lock state to an unlock position in which the locking mechanism is in an unlock state and vice versa owing to normal/reverse rotation of the drive portion or locking/ unlocking operation of manually-operating means, wherein the drive portion comprises two adjacent locking/unlocking drive projections (501 a, 501 b) and two adjacent stopping projections (501c, 501d) opposite the two locking/ unlocking drive projections (501a, 501b), the four projections being spaced from each other circumferentially by approximately 90 degrees, wherein the actuating member comprises a pair of driven portions with which the two locking/unlocking drive projections (501a, 501b) are able to come in contact respectively when the drive portion rotates, the driven portions being spaced from each other so that the actuating member is moved to the unlock position or the lock position by the manually operating means, and contact portions with which the two stopping projections (501c, 501d) are able to come in contact respectively; wherein when one of the two locking/unlocking drive projections (501a, 501b) is positioned between the driven portions and when the drive portion rotates, the locking/ unlocking drive projection (501a, 501b) positioned between the driven portions comes in contact with one of the pair of driven portions thereby moving the actuating member toward the lock position or the unlock position, on the way of the movement the other locking/unlocking drive projection (501a, 501b) which does not move the actuating member comes in between the driven portions at the same time, when the actuating member moves to the lock position or the unlock position, the locking/ unlocking drive projections (501a, 501b) positioned between the driven portions leaves the driven portion, and the stopping projection (501c, 501d) opposite the locking/ unlocking drive projection (501a, 501b) which leaves the driven portion comes in contact with the contact portion thereby stopping rotation of the drive portion. a reversible motor; a rotating object rotated by the motor normally and reversely; a drive portion rotated normally and reversely together with the rotating object; and an actuating member that moves from a lock position in which a locking mechanism of a door is in a lock state to an unlock position in which the locking mechanism is in an unlock state and vice versa owing to normal/reverse rotation of the drive portion or locking/ unlocking operation of manually-operating means, wherein the drive portion comprises two adjacent locking/unlocking drive projections (501 a, 501 b) and two adjacent stopping projections (501c, 501d) opposite the two locking/ unlocking drive projections (501a, 501b), the four projections being spaced from each other circumferentially by approximately 90 degrees, wherein the actuating member comprises a pair of driven portions with which the two locking/unlocking drive projections (501a, 501b) are able to come in contact respectively when the drive portion rotates, the driven portions being spaced from each other so that the actuating member is moved to the unlock position or the lock position by the manually operating means, and contact portions with which the two stopping projections (501c, 501d) are able to come in contact respectively; wherein when one of the two locking/unlocking drive projections (501a, 501b) is positioned between the driven portions and when the drive portion rotates, the locking/ unlocking drive projection (501a, 501b) positioned between the driven portions comes in contact with one of the pair of driven portions thereby moving the actuating member toward the lock position or the unlock position, on the way of the movement the other locking/unlocking drive projection (501a, 501b) which does not move the actuating member comes in between the driven portions at the same time, when the actuating member moves to the lock position or the unlock position, the locking/ unlocking drive projections (501a, 501b) positioned between the driven portions leaves the driven portion, and the stopping projection (501c, 501d) opposite the locking/ unlocking drive projection (501a, 501b) which leaves the driven portion comes in contact with the contact portion thereby stopping rotation of the drive portion.