A width prediction method of a rough rolled material, which predicts a width of the rough rolled material in a hot rolling line including a heating furnace configured to heat a slab, a width reduction pressing device configured to intermittently perform width reduction on the heated slab, a rough rolling mill configured to manufacture the rough rolled material by performing rough rolling on the slab after the width reduction, and a finish rolling mill configured to manufacture a hot-rolled steel sheet by performing finish rolling on the rough rolled material, the width prediction method comprising:
- a step of predicting a width distribution in a longitudinal direction of the rough rolled material by using a width prediction model learned by machine learning, the width prediction model for which
- an input data is data including one or more operational parameters selected from operational parameters of the width reduction pressing device and one or more operational parameters selected from operational parameters of the rough rolling mill, and
- an output data is information on the width distribution in the longitudinal direction of the rough rolled material.