An easy-to-use, inexpensive, and small sheet conveying device, which can stably and separately convey not only sheets of a fixed size that are normally used, but also highly rigid sheets and special sheets, and can further separately convey a bent sheet reliably. In a sheet conveying path switching device having a sheet carrying-in path and a switching separating nail, outlines of two separating/conveying paths out of a plurality of separating/conveying paths positioned on a downstream side of the switching separating nail are configured by a movable belt surface, the two separating/conveying paths being located closer to the separating nail than the other separating/conveying paths.