A machining program preparation apparatus includes a machining region extracting unit (3) that extracts a machining region (300) based on a given three-dimensional part shape (100) and a given three-dimensional material shape (200), an envelope shape generating unit (4) that generates a three-dimensional envelope shape (400) that envelopes the given three-dimensional part shape (100) based on this part shape, a turning region extracting unit (5) that extracts a three-dimensional turning region (500) from the material shape (200) and the envelope shape (400), and a milling region extracting unit (6) that extracts a three-dimensional milling region (600) from the machining region (300) extracted by the machining region extracting unit (3) and the turning region (500) extracted by the turning region extracting unit (5).