A cutter formed by detachably attaching a replaceable blade to a cutter body. The cutter body can include a main body block and slide block. The main body block includes a main body supporting section supporting the replaceable blade back face, and a main body connecting section connecting with the replaceable blade from the front face side. The slide block includes a rear side supporting section supporting the replaceable blade back face, a slide connecting section connecting with and retracting the replaceable blade toward the rear side, and a back side protruding section protruding on the back side in a thickness direction. When attached, the replaceable blade elastically deforms to curve in the thickness direction, the slide block presses toward a main body block side in the thickness direction by elastic force of the replaceable blade, and the back side protruding section engages with a main body block engaged section.