PURPOSE: To provide a clamping mechanism for gut stretching device capable of lessening the wear down at the angle of a semicircular recessed part formed at the joint of a base part by partly cutting away the right and left side faces of a gliding bar for guiding a clamp which clamps this gliding bar with the angle of the semicircular recessed part.

CONSTITUTION: This clamping mechanism is provided with the clamp 11 which consists of a pair of right and left clamping bodies 11a, is provided with the semicircular recessed part 12 at the joint of the base part and clamps the gliding bar 14 with its angle. The right and left side faces of the gliding bar 14 for guiding the clamp 11 are partly cut away 14a. The gliding bar 14 is horizontally fixed onto a sliding plate 16 by a supporting plate 15. The angle part of the semicircular recessed part of the clamp hardly rubs against the gliding bar or does not rub against this bar at all if the position of the clamp is shifted by tilting bringing down the clamp at the time of shifting the position of the clamp.