To provide a method and device for shearing a steel plate for reducing the shearing load by controlling the material (shearing resistance) in the region of the steel plate to be sheared.

The position to be sheared in the steel plate is surface-quenched to the depth 2 mm and hardened, and a shearing blade is applied to the steel plate to shear the steel plate. The steel plate shearing equipment includes a surface quenching device, a marking device, a marking position detecting device, a conveying device, and a shearing machine. The surface quenching device surface quenches the steel plate in the position to be sheared. The marking device applies a mark in the position to be sheared in the surface-quenched steel plate. The marking position detecting device detects the marked position to be sheared. The conveying device conveys the position to be sheared of the steel plate to a shearing position of the shearing machine based on a detection signal from the marking position detecting device.