For establishment of metallurgical bonding technology of bulk metallic glasses, we have tried to weld Pd40Ni40P20 and Zr55Al10Ni5Cu30 bulk metallic glasses having a wide supercooled liquid region and high glass forming ability by three welding methods of friction, pulse-current and explosion We have succeeded in joining bulk metallic glasses to the same bulk metallic glasses or polycrystalline metallic materials. No crystallization was observed in the interface and heat-affected zones. No visible defect was recognized at the interface, showing an achievement of metallurgical bonding of bulk metallic glasses. The tensile strength of the welded bulk metallic glasses was the same as that of the parent bulk metallic glasses.