Abstract: Disclosed is a tool clamping mechanism for use in a machining center, which includes a pivoting member having at opposite ends a pair of fingers for grasping a tool, the pair of fingers being connected by means of a hinge, a rotating block fixedly mounted on a shaft so as to be rotated clockwise and counter-clockwise in a given range by the shaft, the rotating block being rotatably positioned in the center of the pivoting member, a pair of sliders for respectively pushing and pulling the pairs of fingers to open or close, a pair of rotating block links for respectively connecting the rotating block with the pair of sliders, a pair of slider links for connecting each of the sliders with each pair of fingers, and an actuating means for rotating the shaft and thus rotating block, wherein the rotating block is rotated to push or pull the pair of sliders so as to open or close the pairs of fingers through the cooperation of the links.