A numerical controller is provided with a control unit configured to control a machine tool and acquire feedback data in relative positions of a tool and a workpiece, a machining simulation unit configured to perform simulation processing for machining based on a machining program and create the shape of the machined workpiece, and a display unit configured to display the machined workpiece shape created by the machining simulation unit. The machining simulation unit performs machining simulation processing using the feedback data acquired by the control unit, in place of relative movement paths for the tool and the workpiece based on a command by the machining program.