A method or device for computing material requirements which calculates various parts and materials necessary for products to be produced when a production plan is input, in order to reduce the processing time for a material requirements computation. In order to establish the object, the method or device of computing material requirements is provided, which can perform a parallel process without using conventional low level codes. Parts computing means are respectively assigned to items. When the lower parts computing means receives the computation result of the upper parts computing means, it independently executes the computing process if the computation result is sufficient for the parts computation. The process rate of the material requirements computation can be improved by performing the load distribution under a fixed rule, including that to which computer the data of an item is loaded or by which computer an item is processed, when the material requirements are computed in parallel process using plural computers.