Provided is a sliding door device which is capable of retracting a sliding door diagonally. Such a sliding door device 1 includes rails 7a and 7b for guiding the sliding door 2 to move in a retracting direction A from an open position to a closed position with respect to a main body 3 and guiding the sliding door 2 to move forward or backward in a front view of the sliding door 2 until reaching the closed position, a rod-shaped trigger 8 provided on one of the main body 3 and the sliding door 2, and a retracting device 9′ provided on the other of the main body 3 and the sliding door 2 and retracting the trigger 8 while sliding in an axial direction D of the trigger 8 so that the sliding door 2 can move forward or backward.