A method of manufacturing a multi-core ferrule, in which method a plurality of flat-surface metal sheets 2 containing a plurality of apertures 1 of the same size are laminated and fixed together. The plurality of apertures 1 before subjected to lamination and fixing are designed to be in positions and to have diameters such that they communicate with one another to be capable of forming a cavity, whereby the resulting ferrule is highly accurate in diameter and positions of the pores and is applicable to multi-core connectors, devices and so on.