In a printer, a unit for turning over a sheet comprises: a conveying roll provided downstream of a printer head; a top roll and a bottom roll which are rotatably coupled to the front end and the rear end of a swingable link, respectively; and at least one elastic endless belt reeved around the top roll and bottom roll, the swingable link being swingable about the axis of the top roll with the top roll into contact with the conveying roll through the endless belt, and a control mechanism for operating the link so that it is swung down for a first half of a period of time for which a sheet passes through the conveying roll and the top roll, and swung up for the second half.