An inkjet printer that carries out printing by an inkjet method with respect to long continuous paper provided with a perforation at every page break and provided with marginal punch holes in both sides, the inkjet printer comprising: a paper feeding unit that disposes the Z-folded continuous paper; a first pull roller and a second pull roller for conveying the continuous paper; a pin tractor for positioning the continuous paper; a speed-variable motor for applying tension to the continuous paper; a printing unit that carries out printing on the continuous paper by a print head, the printing unit being located between the first pull roller and the second pull roller; and a discharging unit that Z-folds and discharges the continuous paper by a folding machine; wherein the pin tractor has pins and can carry out positioning of the continuous paper by inserting the pins in the marginal punch holes; a pin-tractor encoder is attached to the pin tractor; a reference detecting sensor for detecting a front end of the continuous paper is attached to a side opposed to the pin tractor via the continuous paper; a holding skid for sandwiching the continuous paper abuts the first pull roller, and a driving motor is attached to the first pull roller; a holding skid for sandwiching the continuous paper abuts the second pull roller, and the speed-variable motor is attached to the second pull roller; and the speed-variable motor applies the tension to the continuous paper by increasing a rotating speed of the second pull roller by a predetermined rate to be higher than a rotation speed of the first pull roller, the inkjet printer further comprising back-tension rollers consisting of a plurality of rollers for guiding the continuous paper and, at the same time, applying the tension; wherein, in the conveyance path of the continuous paper, the back-tension rollers are provided between the paper feeding unit and the pin tractor; a back-tension-roller speed-variable motor is attached to at least one roller of the back-tension rollers; and the back-tension-roller speed-variable motor applies the tension to the continuous paper by changing a rotating speed of the roller with respect to the rotating speed of the first pull roller or the second pull roller. a paper feeding unit that disposes the Z-folded continuous paper; a first pull roller and a second pull roller for conveying the continuous paper; a pin tractor for positioning the continuous paper; a speed-variable motor for applying tension to the continuous paper; a printing unit that carries out printing on the continuous paper by a print head, the printing unit being located between the first pull roller and the second pull roller; and a discharging unit that Z-folds and discharges the continuous paper by a folding machine; wherein the pin tractor has pins and can carry out positioning of the continuous paper by inserting the pins in the marginal punch holes; a pin-tractor encoder is attached to the pin tractor; a reference detecting sensor for detecting a front end of the continuous paper is attached to a side opposed to the pin tractor via the continuous paper; a holding skid for sandwiching the continuous paper abuts the first pull roller, and a driving motor is attached to the first pull roller; a holding skid for sandwiching the continuous paper abuts the second pull roller, and the speed-variable motor is attached to the second pull roller; and the speed-variable motor applies the tension to the continuous paper by increasing a rotating speed of the second pull roller by a predetermined rate to be higher than a rotation speed of the first pull roller, the inkjet printer further comprising back-tension rollers consisting of a plurality of rollers for guiding the continuous paper and, at the same time, applying the tension; wherein, in the conveyance path of the continuous paper, the back-tension rollers are provided between the paper feeding unit and the pin tractor; a back-tension-roller speed-variable motor is attached to at least one roller of the back-tension rollers; and the back-tension-roller speed-variable motor applies the tension to the continuous paper by changing a rotating speed of the roller with respect to the rotating speed of the first pull roller or the second pull roller.