An embroidery pattern data processor for sewing an embroidery based on section data representing the locations of the vertexes of polygonal sections dividing a closed area surrounded by a given outline for embroidering the closed area comprises a memory for storing the section data, a designation means for designating starting and ending points read-out means for reading out the section data, a processor for determining the type of sections, for computing running stitch data, and for computing needle location data for embroidering the sections. The running stitch computing means automatically computes a running stitch route within the sections so that the embroidering operation is carried out without producing cross threads which have previously been manually removed.