A printer for printing on a label continuous body consisting of a plurality of labels temporarily attached to a belt-like liner at predetermined intervals, comprising: a feeding unit configured to feed the label continuous body in a feeding direction or in an opposite direction of the feeding direction; a printing unit configured to print the label; a first detecting unit configured to identify a printing start position of the label, the first detecting unit being disposed at upstream side of the printing unit in the feeding direction of the label continuous body; and a second detecting unit configured to detect an end portion of the label, the second detecting unit being disposed at downstream side of the printing unit in the feeding direction, characterized in that the second detecting unit detects a downstream end (Mf) of a first downstream side label as the first of downstream side labels downstream from a first upstream side label for which a mark for detecting position or a gap between labels is first detected by the first detecting unit, and then, the feeding unit feeds the label continuous body in the opposite direction of the feeding direction to the printing start position of the first downstream side label, and then, the printing unit prints on the first downstream side label being fed in the feeding direction while the feeding unit feeds the label continuous body in the feeding direction, and then, the second detecting unit detects a downstream end (Mf) of a second downstream side label following the first downstream side label, and the feeding unit feeds the label continuous body to the printing start position of the second downstream side label, wherein the feeding is performed in the opposite direction of the feeding direction or in the feeding direction depending on an extension of the labels in the feeding direction, and the printing unit prints on the second downstream side label being conveyed in the feeding direction while the feeding unit feeds the label continuous body in the feeding direction, and then, the feeding unit feeds the label continuous body to the printing start position of the first upstream side label identified by the mark for detecting position or the gap, and the printing unit prints on the first upstream side label. a feeding unit configured to feed the label continuous body in a feeding direction or in an opposite direction of the feeding direction; a printing unit configured to print the label; a first detecting unit configured to identify a printing start position of the label, the first detecting unit being disposed at upstream side of the printing unit in the feeding direction of the label continuous body; and a second detecting unit configured to detect an end portion of the label, the second detecting unit being disposed at downstream side of the printing unit in the feeding direction, characterized in that the second detecting unit detects a downstream end (Mf) of a first downstream side label as the first of downstream side labels downstream from a first upstream side label for which a mark for detecting position or a gap between labels is first detected by the first detecting unit, and then, the feeding unit feeds the label continuous body in the opposite direction of the feeding direction to the printing start position of the first downstream side label, and then, the printing unit prints on the first downstream side label being fed in the feeding direction while the feeding unit feeds the label continuous body in the feeding direction, and then, the second detecting unit detects a downstream end (Mf) of a second downstream side label following the first downstream side label, and the feeding unit feeds the label continuous body to the printing start position of the second downstream side label, wherein the feeding is performed in the opposite direction of the feeding direction or in the feeding direction depending on an extension of the labels in the feeding direction, and the printing unit prints on the second downstream side label being conveyed in the feeding direction while the feeding unit feeds the label continuous body in the feeding direction, and then, the feeding unit feeds the label continuous body to the printing start position of the first upstream side label identified by the mark for detecting position or the gap, and the printing unit prints on the first upstream side label.