A stapler comprising: a forming plate configured to shape a leading staple of a staple sheet, which is formed by connecting a plurality of staples extending linearly in a direction perpendicular to an axial direction of the staples, into a U-shape, when viewed from a connection direction of the staples; a face plate provided at a position to be face the leading staple in the connection direction; and a feeding portion configured to, after the leading staple is shaped, feed the staple sheet in the connection direction, and configured to bring a linear staple positioned immediately behind the shaped staple into contact with the face plate, wherein the forming plate includes a first shaping portion that is configured to shape one leg portion of the staple forming a part of the U-shape and a second shaping portion that is configured to shape another leg portion thereof forming another part of the U-shape, the first shaping portion is configured to be insertable and removable at a position facing the face plate, configured to shape the one leg portion by bending a part of the leading staple by being inserted at the position facing the face plate, and configured to retract from the position facing the face plate after shaping, and the second shaping portion is configured to be insertable and removable at the position facing the face plate, and configured to shape the other leg portion by bending another part of the leading staple by being inserted at the position facing the face plate, characterized in that the second shaping portion is configured to retract from the position facing the face plate after the first shaping portion retracts from the position facing the face plate after shaping. a forming plate configured to shape a leading staple of a staple sheet, which is formed by connecting a plurality of staples extending linearly in a direction perpendicular to an axial direction of the staples, into a U-shape, when viewed from a connection direction of the staples; a face plate provided at a position to be face the leading staple in the connection direction; and a feeding portion configured to, after the leading staple is shaped, feed the staple sheet in the connection direction, and configured to bring a linear staple positioned immediately behind the shaped staple into contact with the face plate, wherein the forming plate includes a first shaping portion that is configured to shape one leg portion of the staple forming a part of the U-shape and a second shaping portion that is configured to shape another leg portion thereof forming another part of the U-shape, the first shaping portion is configured to be insertable and removable at a position facing the face plate, configured to shape the one leg portion by bending a part of the leading staple by being inserted at the position facing the face plate, and configured to retract from the position facing the face plate after shaping, and the second shaping portion is configured to be insertable and removable at the position facing the face plate, and configured to shape the other leg portion by bending another part of the leading staple by being inserted at the position facing the face plate, characterized in that the second shaping portion is configured to retract from the position facing the face plate after the first shaping portion retracts from the position facing the face plate after shaping.