A numerical controller which controls a machine tool on the basis of a program instruction analyzes the program instruction to generate movement instruction data, and sets a value of a constant used for speed change on the basis of a physical amount regarding a curvature at a current position on a movement path based on the generated movement instruction data. Then, the numerical controller calculates movement speeds of axes of the machine tool using the set value of the constant used for the speed change, and controls the axes on the basis of the calculated movement speeds.

A numerical controller which controls a machine tool on the basis of a program instruction analyzes the program instruction to generate movement instruction data, and sets a value of a constant used for speed change on the basis of a physical amount regarding a curvature at a current position on a movement path based on the generated movement instruction data. Then, the numerical controller calculates movement speeds of axes of the machine tool using the set value of the constant used for the speed change, and controls the axes on the basis of the calculated movement speeds.