Numerical controller having corner path generation function in consideration of post-interpolation acceleration/deceleration

A numerical controller controls a machine tool with a plurality of control axes so as to compensate an inward turning error by inserting a curved movement path into a corner section between two consecutive blocks. An estimated inward turning amount generated as the corner section is subjected to post-interpolation acceleration/deceleration is calculated based on the radius of curvature of the curve and allowable accelerations of the axes of the machine tool, and such a curved movement path that its inward turning amount has a value obtained by subtracting the estimated inward turning amount from a tolerance is inserted into the corner section if the sum of the estimated inward turning and the inward turning amount of the curve is larger than the tolerance.