To provide molds for the width reduction of a hot steel slab, which can enhance the productivity of a hot rolling line, can prevent the surface defects of a product from being caused due to the damage of the molds and can achieve marked improvement in the cost of the molds and so on, by preventing the surface of the molds in a sheet width reduction press from being damaged so as to extend the life of the molds greatly.

The molds for width reduction are oppositely installed in the direction of the width of the hot steel slab, and are used for reducing the hot steel slab intermittently in the direction of the sheet width. The mold consists of three layers, an external layer 1, an intermediate layer 2 and an internal layer 3, in order of closeness to the reduced surface of the slab. The intermediate layer 2 comprises a material having higher thermal conductivity than the external layer 1, such as copper alloy or aluminum alloy.