Abstract: A striker is at a vehicle body. A door latch mechanism is at a back door and holds it in a closed state for the vehicle body by engaging the striker. The door latch mechanism has a latch, ratchet, latch base, latch shaft, ratchet shaft, latch spring and ratchet spring. The ratchet is formed by a latch locking part which locks the latch so that the latch holds the engagement state with the striker and at a position which waits ingress of the striker in a state that the striker does not engage the latch and a wall surface contact part which behaves as a rotation stopper of the ratchet by contacting to a wall surface of the latch base. The latch locking part and the wall surface contact part are provided so that positions of a center of rotation and a center of gravity of this ratchet correspond practically.