Slab casting method

A slab casting method using a twin-drum continuous casting device manufactures a slab by solidifying molten metal by a pair of rotating casting drums includes calculating estimated sheet thicknesses on both ends in a width direction of the slab from equation 1 ((estimated sheet thickness)=(cylinder screw down position)+(elastic deformation of casting drum)+(casting drum housing screw down system deformation)+(drum profile of casting drum)−(elastic deformation of casting drum at the time of screw down position zero adjustment)) by using a casting drum housing screw down system deformation characteristic indicating a deformation characteristic of housings that support the casting drums and a deformation characteristic of a screw down system that screws down the casting drums obtained before casting of the slab starts, and controlling screw down positions of cylinders provided on both ends in a width direction of the casting drums.