A bead core manufacturing apparatus (1) comprises an annular former (4) having an outer peripheral surface (40) on which a bead wire (w) is woundable into a bead core. The former (4) comprises a set of segments (41), which are divided circumferentially of the former, and which have radially outer surfaces collectively forming the outer peripheral surface (40). The segments (41) are movable in respective radial directions of the former so that the outer peripheral surface (40) has plural outside diameters, and a bead wire can be wound into plural kinds of bead cores having different inside diameters.