To provide a sheet conveyer capable of correcting stably a skew, an image forming device and an image reader.

This sheet conveyer is provided with conveying roller pairs 34 comprising a lower roller 301 and an upper roller 14 brought into pressure contact with the lower roller 301 contactably and separably and for conveying a sheet S to a skew correction part, in a sheet conveying directional upstream of the skew correction part, and each conveying roller pair 34 is constituted to bring the upper roller 14 into contactable and separable with/from the lower roller 301, when correcting the skew of the sheet by the skew correction part. Flanges 302 are provided to be projected in an upper side of a roller part 301a, in axial-directional both sides of the roller part 301a constituting the lower roller 301, and the sheet S is supported from an under side by the flanges 302 when the upper roller 14 is separated from the lower roller 301.