Abstract: The mechanical machining center is associated with a magazine for the tools in which the tools are collected in two horizontal rows superposed on vertical frames (pallets) transportable by means of a rotatable handling device from the magazine to a position in which an exchange arm withdraws the tools and brings them to the spindle of the working head. The magazine is composed of a fixed structure with a variable number of modules disposed in the form of a fan around the rotatable handling device and in which the pallets complete with tools are accommodated. The pallets may be transported manually or with the aid of wire-guided trolleys from a central magazine to each module. The handling device comprises a rotatable carousel structure on which two cage-like frames for supporting the pallets are pivoted in diametrically opposed position.Normally, one of the two frames is in a loading position, while the other frame is in an exchange position close to the exchanger arm.