To provide a punch data generating device that generates punch data for forming penetrations on a sheet of workpiece with an embroiderable sewing machine and that allows cutting of the workpiece along the outline of a given pattern, wherein the generated punch data allows the user himself/herself to detach the outline of the generated pattern from the workpiece with ease.

A control circuit controls execution of a penetration forming operation on the workpiece W based on the punch data. Based on predetermined line data, the control circuit generates the punch data including: draw data for drawing predetermined pattern(s) on the workpiece W through formation of a plurality of penetrations H; cut data for cutting along the outline of the pattern(s) ; and auxiliary cut data for forming cut E which helps the user when detaching the outline of the pattern from workpiece W.