Disclosed are a device, a system, and a method for setting standard work times that take real-world manufacturing capabilities into account. Provided is a standard work time calculation device (10), which analyzes fluctuations in production line assessment indices on a per time period basis, and computes standard work times for each region, as classified according to the degree of fluctuation. The standard work time calculation device (10) comprises a fluctuation coefficient computation unit (111), which computes coefficients of fluctuation for the assessment indices, a fluctuation region identification unit (112), which identifies regions of fluctuation with coefficients of fluctuation that are greater than or equal to predetermined thresholds, and a standard work time computation unit (113), which computes standard work times for regions of fluctuation.