To provide an NC machining information creating device and a creating method capable of efficiently creating such machining information as not to be influenced by a skill of a worker.

Plural machining conditions are preliminarily stored in a machining information storage part 31. A machining area calculation processing part 22 extracts a machining area from the difference between drawing data of machining components inputted by an input device 1 and drawing data of the shapes of materials and creates a machining block. A machining condition setting processing part 23 retrieves the machining conditions stored in the machining conditions storage part 31 by every created machining block and selects the optimal machining condition. A machining information output processing part 24 outputs the machining information created based on the machining condition selected by the machining condition setting processing part 23 to an output device 4.