Spatter detection method and method for manufacturing welded member

A spatter detection method for detecting an occurrence of sputter in resistance spot welding, the resistance spot welding being welding in which a material to be welded, obtained by stacking a plurality of metal members on one another, is joined by sandwiching the material to be welded between a pair of electrodes and feeding an electric current therethrough, wherein

• the occurrence of sputter is detected based on a change in a volume of a molten part of the material to be welded, wherein
• the pair of electrodes comprises a first electrode, and a second electrode movable relative to the first electrode in a direction in which the metal members are stacked on one another, and
• the change in the volume of the molten part is calculated based on a change in a distance between the first and second electrodes, and a change in an internal stress of the molten part.