Abstract: A tool changing installation for an automatic machine-tool including a tool magazine having a plurality of independently rotatable drums coaxially aligned. Each drum includes a large radial recess opening on its periphery and a plurality of tools angularly disposed around the periphery thereof. A tool transporting carriage moves parallel with the axis of the drums to selectively remove and replace the tools in the drums. A tool being removed or replaced passes on the transporting carriage through the recesses of the other drums to or from a tool loader. The tool loader takes the tools from the transporting carriage and loads them in the machine-tool and removes tools from the machine-tool and loads them in the transporting carriage to be replaced in the drums.