To perform attachment of a punch and a die efficiently and with high accuracy.

A method for attaching a die includes: preparation of a replaceable unit in which a die and a punch are incorporated with accuracy during punching of a material; placement of the replaceable unit on a placement surface so that a lower surface of the die of the replaceable unit comes into contact with the placement surface in a punching device; fixing the die on the placement surface; moving an upper die so that the lower surface of the upper die for moving the punch in the moving direction comes into contact with the upper surface of the punch; and fixing the upper die and the punch.