To provide an epoch-making cutting blade capable of smoothly cutting a channel material and an angle material in even cutter and cutting device manufacturable by simple constitutions by improving a conventional linear blade edge.

When a blade edge of a cutting blade plate 2 for cutting the channel material 1 by cutting from a corner edge 3 of a cutting base end side of the channel material 1 rotated and locked by making one end side as a fulcrum to a corner edge 4 on an opposite side is not made a linear blade edge and a horizontal piece part 5 of the channel material 1 is cut together with a suspended piece part 10 on the one end side toward the corner edge 4 on the opposite side from the corner edge 3 on the cutting base end side of the channel 1, a protruding blade part 6 piercing by the rotation is protruded and formed in mid-way of the blade edge at a position away from not a cutting end 7 but a tip side while the cutting, cutting is performed up to a position pierced by the protruding blade part 6 at the blade edge on a base end side from the protruding blade part 6, remaining part from the position pierced at the blade edge on the tip side from the protruding blade part 6 is cut and chips 8 are separated by making the pierced position as a boundary.