To simplify the hanging work of a door in a sliding door device.

In this sliding door device comprising rails 13, 14 fixed to a wall face of a building, doors 5, 6 hung down from the rails through a door roller 15, and door pockets 7, 8, a tail part 43 of the door stayed in the door case when the door is closed, is thinned in comparison with a main body part of the door, to a degree to be passed through an opening 44 of the door pocket into the door pocket.