A numerical controller outputs a feature amount of time-series data generated in relation to machining. The numerical controller is provided with a data acquisition unit configured to acquire the time-series data from a sensor, a feature amount calculation unit configured to sort the time-series data by their values, extract a set of the time-series data with variations of the values not higher than a predetermined threshold, and calculate the feature amount representative of the set, and a feature amount output unit configured to output the feature amount.