Machining step monitoring apparatus and machining step monitoring method

A machining step monitoring apparatus includes a data segmentation unit, a data length adjuster, and a determination processor. The data segmentation unit defines machining start time and machining end time of each single cycle, and segments, from a first physical quantity that temporally changes during the cycle machining in the machining machine, first measurement data indicating the first physical quantity from the machining start time to the machining end time for each single cycle. The data length adjuster generates the second measurement data by adjusting the data length of the first measurement data to match with the data length of the determination reference data indicating, as a reference, a change in the first physical quantity during the single cycle when the machining machine is normally operating. The determination processor compares the second measurement data with the determination reference data to determine whether the machining machine is normally operating.