A machining time predicting apparatus of a numerically controlled machine tool divides a tool path into a plurality of segments, obtains a speed in a tangential direction of each of the divided segments, calculates a time taken for the tool to move on each segment, and obtains the total of the calculated times taken for the tool to move on each segment as a tool moving time, in order to calculate a time (tool moving time) taken for the tool to move on the designated tool path according to an NC command.