The purpose of the present invention is to easily select a curved-surface compound die tool that is appropriate for cutting of a structural model having a double curved surface. A tool selection unit (21) has an analysis unit (211) and a selection unit (212). The analysis unit (211) determines a pick feed direction and the feed direction of a tool on the basis of information relating to the shape of a machining region including a double curved surface or a machining surface in the machining region, and creates parameter information in which at least a value relating to the smallest curvature radius in the machining surface and a value relating to the largest curvature radius in the pick feed direction are recorded. The selection unit (212) selects a tool to use for machining the machining region on the basis of the parameter information, from among a plurality of tools having an end cutting edge formed in a curved-surface shape and a side cutting edge formed in a curved-surface shape having a curvature radius different from the curvature radius of the curved surface of the end cutting edge.