An edge detection unit is arranged in a conveying portion conveying a sheet and detects the edge of the sheet in the width direction perpendicular to the sheet conveying direction. A light source unit is arranged opposite the sheet. A detecting portion holder holds the edge detection unit and the light source unit. A conveying roller pair positions the sheet conveyed toward the edge detection unit. A unit housing houses the detecting portion holder and the conveying roller pair. The edge detection unit has a contact glass making contact with the sheet. The light source unit has a facing glass facing the contact glass. One glass out of the contact glass and the facing glass is inclined downward at a first angle with respect to the tangent line, which passes through the nip portion between the conveying roller pair, toward the downstream side in the sheet conveying direction.

An edge detection unit is arranged in a conveying portion conveying a sheet and detects the edge of the sheet in the width direction perpendicular to the sheet conveying direction. A light source unit is arranged opposite the sheet. A detecting portion holder holds the edge detection unit and the light source unit. A conveying roller pair positions the sheet conveyed toward the edge detection unit. A unit housing houses the detecting portion holder and the conveying roller pair. The edge detection unit has a contact glass making contact with the sheet. The light source unit has a facing glass facing the contact glass. One glass out of the contact glass and the facing glass is inclined downward at a first angle with respect to the tangent line, which passes through the nip portion between the conveying roller pair, toward the downstream side in the sheet conveying direction.

A medium feeding device includes: a supplier that causes multiple loaded recording media to levitate and be separated from each other by supplying air to the recording media from an edge of the recording media; a feeding unit that feeds, in a feeding direction, an uppermost one of the recording media separated by the supplier; a contact section that comes into contact with a lateral edge of the multiple recording media from a lateral side of the multiple recording media; a projection unit that is provided at the contact section and onto which an image of the lateral edge of the multiple recording media is projected in the feeding direction; and an image capturing unit that is disposed in the feeding direction relative to the multiple recording media and that captures the image projected on the projection unit in a state where the multiple recording media are supplied with the air from the supplier.