To rationally arrange a power unit 20, a cable 21' for opening a door, and a cable 21" for closing the door of a power slide device.

This power slide device has the power unit 20 provided in an internal space of the slide door 11, the cable 21' for opening the door in which a tip side is extended backward in a lower rail 14 through a front side of a pulley 22 of a lower bracket 18, and the cable 21" for closing the door in which a tip side is extended forward in a center rail 16 through a rear side of a pulley 23 of a center bracket 19.