PURPOSE: To efficiently and smoothly cut a molten glass and to obtain the gob without any defect such as a shear mark by rotating a couple of cutting blades always horizontally directed on a vertical circle cocurrently with the molten glass without being stopped.

CONSTITUTION: The coupled upper and lower driven gears 22 and 23 are rotated by a pulse motor 28 through coupled driving gears 26a and 26b, and a blade 1 fixed to a blade holder 3 through the crankshafts 12a and 12b and always horizontally directed is continuously rotated on a vertical circle. A blade 2 confronted with a falling glass 30 in between is rotated in the same way and intercrossed with the blade 1. In this case, the driving gears and driven gears 22 and 23 are placed on the apex of an isosceles triangle with a line connecting the centers of the driven gears 22 and 23 as the base. Accordingly, the vertical length of the holder 3 is reduced by decreasing the length of the base, the weight is reduced, the rotation inertia of the holder is reduced, and hence the contact time with the glass is minimized by rotating the blade at high speed.