1. A design and manufacturing management system composed of a production plan management server machine, a design management server machine and a manufacturing management server machine comprising: a feedback management loop which connects the manufacturing management server machine to the design management server machine; and a production plan management unit of the production plan management server machine for making the production plan and instructing the design management server machine to design a product, wherein the design management server machine comprises: a design processing unit for managing a design drawing of a product, which has been created by means of computer aid, by storing the design drawing in a design drawing database, a drawing edit management unit for managing an E-BOM created from the design drawing by storing the E-BOM in an E-BOM database, and for notifying the manufacturing management server machine of design completion, and a design change display processing unit for causing design change permitted range and forbidden range to be displayed, upon design change of the product, in accordance with design change verification information which is feedback information from the manufacturing management server machine and has been created and updated in the manufacturing management server machine in a design change verification database; and the manufacturing management server machine comprises: a part order management unit for requesting confirmation when receiving the design completion notice from the drawing edit management unit, and managing a M-BOM, to which preparation information including an order instruction and a manufacturing instruction of a part is added and which has been created in accordance with the E-BOM after a confirmation response is input, by storing the M-BOM in a M-BOM database, and a design change verification processing unit for managing the design change verification information which has been created in accordance with the preparation information of the M-BOM by storing the design change verification information in the design verification database; wherein the design change verification processing unit determines the design change permitted range and forbidden range in accordance with a progress state of the manufacturing instruction and order instruction of the part in the preparation information, and updates the design change verification information.