The present invention provides a cutting blade used in the layer-laminated body cutting method. It will not produce the discarded materials, such as stripped slices or broken slices, during the cutting process for the layer-laminated brittle material substrate and the layer-laminated body of a resin membrane. The surface of the brittle material substrate will also not have damage. The present invention, with the glass substrate on the opposed surface side of one surface side of the resin membrane, forms the crevice in the thickness range of 10% to 100% of the glass substrate in a generally vertical direction. It presses the cutting blade at the surface of the resin membrane corresponding to the crevice position or neighboring positions and makes their blades back and forth relative to the layer-laminated body. Thereby it forms a cutting opening in the resin membrane and makes the cutting opening to reach the thickness range above 90% of the resin membrane and does not reach the range of the glass substrate.