SLIDING DOOR DEVICE FOR VEHICLE

A sliding door device for a vehicle includes a door configured to open or close a door opening portion formed in a vehicle body; a door arm including a first end portion rotatably connected to an end portion of the door, and a second end portion configured to be movable along a side sill of the vehicle body; a lower slider coupled to the second end portion of the door arm and configured to be rectilinearly movable along the side sill of the vehicle body; a lower arm plate connecting the second end portion of the door arm and the lower slider and configured to perform a cycloidal rotation and a rectilinear movement when the lower slider moves along the side sill; and a first rail providing a route through which the lower arm plate performs the cycloidal rotation and the rectilinear movement when the lower slider moves along the side sill.