To provide a rotary blade for cutting and a cutting device capable of coping with ends of a large amount of workpieces at a time by cutting.

This cutting device 10 is provided with a base 18 rotatably supported by a vertical frame 14. The base is provided with a surface plate 22 in the lower end of its front surface and a liftable and lowerable mount 30 in its upper part vertically movably along a lift guide 28. In the mount 30, a rotary shaft 34 is supported by a bearing 32, and the rotary blade 36 is attached to the rotary shaft 34. An air cylinder 40 is provided in the rear surface of the base 18, and the rod of the air cylinder 40 is connected to the mount 30 by an S-shaped connecting plate 48. Therefore, when the rod of the air cylinder 40 is displaced downward, the mount 30, that is, the rotary blade 36 is also lowered. As it is lowered, cutting blades formed in a plurality of blade sections provided with intervals in the circumferential direction of the rotary blade 36 are contacted with corner sections of the workpieces supported on the surface plate 22 successively.