PURPOSE: To accurately chuck even a compact glass tube by providing a glass tube fixed section that engages with the end of the glass tube and holds it, following the engagement between a guide and a receiver, in an attachable and detachable holder with the receiver.

CONSTITUTION: A glass tube 1 is supported by the glass tube chuck devices 4 and 5 of a mold unit 3 and the devices 4 and 5 are provided at the tip of bending levers 6 and 7. The devices 4 and 5 are symmetrical mutually and their basic configuration and functions are the same. The device 4 has a support section 15 on which the end 1a of the glass tube 1 is loaded and a holder 16 that can be attached and detached to the support section 15. The support section 15 has a guide 18 consisting of a recessed section 17 and a protruded section that is protruded in the axial direction. On the other hand, the holder 16 is provided with a receiver section 20 that engages with the guide 18 so as to freely be inserted and removed and a glass tube fixed section 21 that can engage with the opening section 1b of the glass tube 1. As a result, the end section can accurately be chucked even in a compact glass tube.