A sheet conveying device, that can be included in an image forming apparatus, includes a first conveying unit to convey a sheet in a first sheet conveying direction, a second conveying unit to convey the sheet conveyed by the first conveying unit in a second sheet conveying direction that is different from the first sheet conveying direction, a first sheet conveying path provided between the first conveying unit and the second conveying unit, a belt-type sheet conveying unit to the holding section of the second conveying unit, and a positioning control mechanism to move and position the first supporting member and the second supporting member in respective directions different from each other. The belt-type sheet conveying unit includes a belt, a first rotary belt holding member, a second rotary belt holding member, a first supporting member, and a second supporting member.