PURPOSE: To rapidly convert image data into vector data.

CONSTITUTION: This vectorizing device consists of an outline extracting part a 101 and plural vectorizing processing part a 102, the extracting part a 101 scans an image data storing part 103, traces outlines until an unextracted outline disappears and stores the traced results in an outline data storing part 104. Each of processing part a 102 retrieves the storing part 104, and when unprocessed outline data exist, reads out the data, executes the vectorizing processing of the data and stores the processed result in a vectorized data storing part 105. The outline extracting processing and plural vectorizing processing are executed in parallel. Consequently image data can rapidly be vectorized.