A button making device capable of simply exchanging a first pressed mold, a second pressed mold, and a pressing mold so as to produce buttons of different sizes; a polygonal button whose front surface plate is dome-wise curved and has its shape fixed; and such a button making device, are provided. The button making device has a sliding platform, two pressed molds, a fixed member, a pressing shaft, a pressing mold, and an operation mechanism. The pressed molds are provided on an attachment member which is removably attached to the sliding platform. The pressing mold is removably attached to a lower end of the pressing shaft using magnetic force. The present invention can be used for a button making device which can easily form a metal button by press processing which can be used as an accessory adhered to clothes or the like by a pin or the like.