To provide a device with a better handleability for preventing a sliding door from rebounding.

A closing action brings the sliding door 2 into contact with a side board body 3, so that a hook part 52 of a latch body 29, which is mounted on the sliding door 2, can be engaged with an engaging groove part 9 of an engaging tool 6 which is mounted on the body 3. When the hard closing action makes the sliding door 2 collide against the body 3, a state of engagement with the engaging member 6 by the latch body 29 is fixed by oscillation of an oscillating body 27 which is mounted on the sliding door 2. The sliding door 2 can be prevented from bouncing when colliding against the body 3. The fixation of the state of the engagement with the engaging member 6 by the latch body 29 is released by a return to an oscillating action of the oscillating body 27, which is produced when the sliding door 2 collides against the body 3. The sliding door 2 can be smoothly opened. Handleability in the opening/closing actions of the sliding door 2 can be improved.