A printing labeler having a label restraining and guiding system with a deflection member for turning back only the backing sheet of a continuous label strip composed of a backing sheet having a label peel-off layer and a plurality of labels provisionally attached to the backing sheet to thereby peel the labels from the backing sheet, a platen that supports lateral end portions of the deflection member, a pair of left and right side plates that support the platen and a label guide piece that faces the platen and guides the continuous label strip toward the deflection member and the label guide piece integrally has a pair of left and right engagement flange portions engageable with a pair of left and right engagement grooves formed in the pair of left and right side plates, a stop portion that connects upstream ends of the engagement flange portions and a deflection guide portion that connects downstream ends of the engagement flange portions and that a surface of the platen faces a vacant space enclosed by the engagement flange portions, the stop portion and the deflection guide portion.