A high speed rotary body for false-twisting comprising a tubular body in the hollow portion of which a pin element is perpendicularly fixed. The yarn to be crimped is fed into the hollow portion, looped with one turn around the pin element and delivered to a take-up bobbin. The pin element is integrally formed with three portions i.e. a smaller cylinder, a larger cylinder at one of the ends of the smaller cylinder and a truncated conical portion at the other end thereof. The intersection of the smaller and larger cylinders forms a step. When the incoming yarn portion precedes to touch the step, this portion occupies the center of the tubular body so as not to balloon during the crimping operation.