Numerical-control machining-program creation device

A numerical-control machining-program creation device that creates a numerical-control machining program including turning machining based on shape data of a workpiece, comprising:

• a turning sectional-shape generation unit that generates a three-dimensional turning shape designating a turning shaft as a rotation central axis from shape data of a workpiece, and generates a two-dimensional turning sectional shape based on the generated turning shape;
• a turning-machining removal-shape generation unit that generates a first turning-machining removal shape indicating a shape to be removed by turning machining based on the turning sectional shape;
• a turning-groove-shape extraction unit that extracts a convex shape, having a groove width equal to or less than a set groove width and a groove depth equal to or less than a set groove depth, as a turning groove shape from the first turning-machining removal shape;
• and
• a numerical-control machining-program creation unit that creates a numerical-control machining program for turning machining based on a second turning-machining removal shape obtained by separating the turning groove shape from the first turning-machining removal shape.