A machining program editor that edits a machining program in which a machining path for a wire electrode of a wire electrical discharge machine is set, the machining program editor including: a path determination unit configured to determine whether or not the machining path includes a linear path section that crosses a boundary line between a thick portion of a workpiece and a thin portion of the workpiece, a thickness of the thin portion being smaller than a thickness of the thick portion in an extending direction of the wire electrode; and a path compensator configured to compensate the machining path so as to form, in the thin portion over a predetermined distance, a protrusion projecting outward from the boundary line when the path determination unit determines that the linear path section is included.