Abstract: A method of measuring the moving velocity of a linear object which is moving while vibrating, the method comprising the steps of illuminating the linear object with a flat laser beam having a width larger than the amplitude of vibration, the linear object moving in the direction of its length and vibrating perpendicular to the longitudinal direction; receiving the scattered light from the linear object by a photoelectric conversion device through a finite-sized elliptic or slit aperture disposed with the direction of its minor axis matching the direction of movement of the linear object; and cutting off the d.c. component of a speckle signal from the photoelectric conversion device, counting the number of zero-crossings per second of the resulting signal and converting the count value to a signal representing the longitudinal moving velocity of the linear object.