to the oscillator 3 and a conveyor means 7 for conveying a carbon fiber fabric 20 continuously along an oscillator side face 4a of the guide plate 4 the ultrasonic wave oscillator 3 is mounted rotatably about an axis which is perpendicular to the oscillator side face 4a of the guide plate 4 and means 3a for rotating the oscillator about the said axis is provided whereby it is made possible for the apparatus to effect a more uniform disintegration of yarn further by inclining the oscillator 3 side face 4a of the guide plate 4 with respect to the water surface of the water vessel 2 as shown in fig2 or by forming it as a curved surface which is convex on the oscillator side as shown in fig3 it is made possible for the apparatus to effect the yarn disintegrating operation more efficiently and uniformly a carbon fiber fabric 20a to be disintegrated is conveyed by the conveyor means 7 and passes the ultrasonic wave oscillator 3 side of the guide plate 4 at this time ultrasonic wave is applied to the thus passing carbon fiber fabaric now indicated at 20b so that the fabric 20b is brought into pressure contact with the guide plate 4 by virtue of the acoustic pressure and thereby spread out.