Abstract: An automatic tool-changing arm of an automatic tool changer applicable to a machine tool, primarily comprises an immovable platform, a movable platform located below the immovable platform, a platform driving device driving the movable platform to vertically move with respect to the immovable platform, a gear assembly settled on the moveable platform and an arm body fixedly attached to the movable platform and to be rotated by the gear assembly, wherein the arm body has two ends each equipped with a clamp driving device and a power clamp. Thereby, the arm body can perform vertical movements and horizontal rotations precisely and stably so as to enhance the reliability of the tool-changing arm.

Abstract: A tool magazine of an automatic tool changer applicable to a machine tool, comprises a magazine body and a plurality of tool holders each being slidably attached to the magazine body and holding a tool head. The tool magazine is characterized by that the tool magazine includes a tool-delivering mechanism for delivering the tool holder that holds the tool to a predetermined position away from the magazine body and disengaging the tool from the tool holder.