To provide an oscillating shearing device capable of accurately preventing the breakage of a clamp cylinder rod for connecting a shear blade with a shearing device body.

The shearing device is provided with an anti-swing member 5 for preventing the swinging of the shear blade 3 (upper shear blade 11) in a longitudinal traveling direction of a steel plate at a position adjacent to ends in the vicinity of the traveling direction 8 of the steel plate of the shear blade 3 (upper shear blade 11), respectively.