Synthetic resin spout stopper

A synthetic resin spout stopper to be applied to a paper container having at least a synthetic resin film laminated to an inner surface or outer surface thereof, comprising:

• a protruding tubular wall allowed to protrude through or in succession to a spout hole formed in the container;
• and
• an annular flange wall extending out radially outwardly from an outer periphery of a lower end part of the protruding tubular wall,
• wherein an upper surface or lower surface of the annular flange wall is welded to an inner surface or outer surface of the container, and an annular score is formed in an inner peripheral edge part of the annular flange wall,
• characterized in that an annular additional score is formed in the inner peripheral edge part of the annular flange wall in such a manner as to be disposed adjacent to the annular score radially outwardly of and/or radially inwardly of the annular score.