The present invention relates to a method and apparatus for inspecting the quality of laser welding by monitoring the size of a metal molten pool (i.e., weld metal) during a laser welding process. The present invention provides a method and apparatus for inspecting the quality of laser welding, in which a new type laser welding quality inspection system is implemented in which one sensor signal and one filtered electrical signal of the plasma light can be used to perform a correct welding quality inspection through the development of a filtering method of an electrical signal of the plasma light, thereby facilitating a laser welding quality management and making possible its example application to a vehicle body laser welding process.