A stapler configured to bind a workpiece (P) using a staple made of a non-metal soft material, the staple having a crown portion and a pair of leg portions formed by bending both longitudinal ends of the crown portion toward one direction, the stapler comprising: a placing base on which the workpiece (P) is placed; a penetrating part that includes a pair of cutting blades spaced apart from each other according to a length of the crown portion of the staple and causes the cutting blades to penetrate from one surface of the workpiece (P) placed on the placing base to the other surface thereof; an opening that is provided on the placing base so that the one pair of cutting blades and the one pair of leg portions of the staple inserted into the workpiece (P) pass through the opening ; and a pressing portion that is provided in the opening of the placing base and suppresses deformation of the workpiece (P) caused by a force applied to the workpiece from the cutting blades when the cutting blades penetrate the workpiece , characterized in that the pressing portion is configured such that a pressing surface facing the other surface of the workpiece (P) placed on the placing base is on the same plane as a placing surface of the placing base when the cutting blades penetrate the workpiece (P), the stapler includes a cutting blade guide that suppresses the one pair of cutting blades penetrating the workpiece (P) from being falling down inward, and the pressing portion is provided in the cutting blade guide . a placing base on which the workpiece (P) is placed; a penetrating part that includes a pair of cutting blades spaced apart from each other according to a length of the crown portion of the staple and causes the cutting blades to penetrate from one surface of the workpiece (P) placed on the placing base to the other surface thereof; an opening that is provided on the placing base so that the one pair of cutting blades and the one pair of leg portions of the staple inserted into the workpiece (P) pass through the opening ; and a pressing portion that is provided in the opening of the placing base and suppresses deformation of the workpiece (P) caused by a force applied to the workpiece from the cutting blades when the cutting blades penetrate the workpiece , characterized in that the pressing portion is configured such that a pressing surface facing the other surface of the workpiece (P) placed on the placing base is on the same plane as a placing surface of the placing base when the cutting blades penetrate the workpiece (P), the stapler includes a cutting blade guide that suppresses the one pair of cutting blades penetrating the workpiece (P) from being falling down inward, and the pressing portion is provided in the cutting blade guide . the pressing portion is configured such that a pressing surface facing the other surface of the workpiece (P) placed on the placing base is on the same plane as a placing surface of the placing base when the cutting blades penetrate the workpiece (P), the stapler includes a cutting blade guide that suppresses the one pair of cutting blades penetrating the workpiece (P) from being falling down inward, and the pressing portion is provided in the cutting blade guide . <EOS>