A brake disc manufacturing method, the method comprising: a porous metal block preparation operation for preparing a porous metal block having a plurality of pores therein; and an insert casting operation for mounting the porous metal block in a mold and casting a disc plate material to manufacture a brake disc; wherein the porous metal block preparation operation comprises an operation for preparing an open-cell-type porous metal block having therein a plurality of pores connected to each other and fillable with a filler; wherein the method further comprises: a filler filling operation for filling the filler in the open-cell-type porous metal block prepared in the porous metal block preparation operation, after the porous metal block preparation operation such that cast iron and the disc plate material do not permeate thereinto in the insert casting operation; a filler removal operation for removing the filler filled in the brake disc manufactured in the insert casting operation after the insert casting operation; a bridge hole generation operation for generating bridge holes in the porous metal block; and a hole filler filling operation for temporarily filling a hole filler to be removed before the insert casting operation or to be melted away in the insert casting operation, e.g. sand, expanded polystyrene, or paraffin wax, in the bridge holes before the filler filling operation; and wherein the method further comprises: a hole filler removal operation for removing the hole filler temporarily filled in the bridge holes; and a boundary filler removal operation for removing the filler filled in boundaries between the porous metal block and a casting material by using an air blower such that cast iron and the disc plate material partially permeate into and are firmly fixed to the boundaries in the insert casting operation after the filler filling operation. a porous metal block preparation operation for preparing a porous metal block having a plurality of pores therein; and an insert casting operation for mounting the porous metal block in a mold and casting a disc plate material to manufacture a brake disc; wherein the porous metal block preparation operation comprises an operation for preparing an open-cell-type porous metal block having therein a plurality of pores connected to each other and fillable with a filler; wherein the method further comprises: a filler filling operation for filling the filler in the open-cell-type porous metal block prepared in the porous metal block preparation operation, after the porous metal block preparation operation such that cast iron and the disc plate material do not permeate thereinto in the insert casting operation; a filler removal operation for removing the filler filled in the brake disc manufactured in the insert casting operation after the insert casting operation; a bridge hole generation operation for generating bridge holes in the porous metal block; and a hole filler filling operation for temporarily filling a hole filler to be removed before the insert casting operation or to be melted away in the insert casting operation, e.g. sand, expanded polystyrene, or paraffin wax, in the bridge holes before the filler filling operation; and wherein the method further comprises: a hole filler removal operation for removing the hole filler temporarily filled in the bridge holes; and a boundary filler removal operation for removing the filler filled in boundaries between the porous metal block and a casting material by using an air blower such that cast iron and the disc plate material partially permeate into and are firmly fixed to the boundaries in the insert casting operation after the filler filling operation. a filler filling operation for filling the filler in the open-cell-type porous metal block prepared in the porous metal block preparation operation, after the porous metal block preparation operation such that cast iron and the disc plate material do not permeate thereinto in the insert casting operation; a filler removal operation for removing the filler filled in the brake disc manufactured in the insert casting operation after the insert casting operation; a bridge hole generation operation for generating bridge holes in the porous metal block; and a hole filler filling operation for temporarily filling a hole filler to be removed before the insert casting operation or to be melted away in the insert casting operation, e.g. sand, expanded polystyrene, or paraffin wax, in the bridge holes before the filler filling operation; and wherein the method further comprises: a hole filler removal operation for removing the hole filler temporarily filled in the bridge holes; and a boundary filler removal operation for removing the filler filled in boundaries between the porous metal block and a casting material by using an air blower such that cast iron and the disc plate material partially permeate into and are firmly fixed to the boundaries in the insert casting operation after the filler filling operation. a hole filler removal operation for removing the hole filler temporarily filled in the bridge holes; and a boundary filler removal operation for removing the filler filled in boundaries between the porous metal block and a casting material by using an air blower such that cast iron and the disc plate material partially permeate into and are firmly fixed to the boundaries in the insert casting operation after the filler filling operation.