To provide a machining time estimating apparatus capable of calculating machining time with high precision.

This estimating apparatus comprises a database 22 for storing actual operating time data of an auxiliary function, an actual operating time calculating means 21 for updating the data stored in the database 22, and an operating time estimating means 24 for analyzing an NC program for each block, calculating the estimated operating time of shaft movement based on the analyzed result, searching for the database 22 to estimate the operating time of the auxiliary function, and calculating the estimated operating time for each block and the total estimated machining time based on the obtained shaft movement estimated operating time and auxiliary function estimated operating time.