An information processor performs simulation processing based on information on a workpiece and a machining program and specifies an air-cut path, which is a tool path in which the tool is not in contact with the workpiece, for each of blocks included in the machining program, based on the result of the simulation processing. Moreover, the apparatus calculates a time required for a movement in the air-cut path for each block and changes the display mode of the block on a screen based on the calculated time.