To provide a knock-off bolt which is surely shear-fractured by an assumed load, which makes a fracture surface almost perpendicular to a bolt shank, and which makes elongation until fracture small.

A knock-off bolt is shear-fractured when two members are joined and a load parallel to joint surfaces of the members and equal to/exceeding a predetermined magnitude is applied to the members. A bolt shank 3 becomes hollow by providing a shaft hole 5 along an axial direction from a bolt head 4 in the bolt shank 3. An annular notch part 6 is provided on the outer periphery of this hollow part.