WELDING METHOD AND WELDING APPARATUS FOR SECONDARY BATTERY, AND MONITORING METHOD AND MONITORING APPARATUS FOR SECONDARY BATTERY WELDING PROCESS

The present invention relates to: a welding method and a welding apparatus for a secondary battery capable of emitting a laser beam into the lower can; and a monitoring method and a monitoring apparatus for a secondary battery welding process capable of checking a welded state during the welding. [0002] The welding apparatus according to the present invention comprises: a laser irradiation apparatus for welding an electrode tab to a lower can by emitting a laser beam to a center hole of the electrode assembly; and a jig for protecting the electrode assembly when the laser beam is emitted. [0003] The monitoring apparatus according to the present invention comprises the jig and the laser irradiation apparatus, and the laser irradiation apparatus comprises a welding laser irradiation device, an illumination laser irradiation device, and an image sensor. Here, the welding laser beam and the illumination laser beam are emitted vertically from a top side of the center hole.