CAP FOR OPENING OF SYNTHETIC RESIN CONTAINER

PROBLEM TO BE SOLVED: To provide a cap for an opening of synthetic resin container in which an outflow opening is formed to have a planed shape and an appropriate quantity of liquid can be poured out. SOLUTION: A bottom plate 8 hermetically sealing the container opening is formed in the inside of the cylindrical external wall 4 in the body 1 fixed to the container opening, and a weakened line 9 forming the outflow opening by cutting the peripheral edge 9a is formed at the bottom plate 8. The weakened line 9 has such a form that a waterdrop-shaped air hole D formed at one end of a slender rectangular aperture C and a circular hole E formed at the other end are connected to each other. Accordingly, when the container is inclined, the outflow opening is not covered with liquid and hence, as air can easily enter the container, the liquid can be poured so as to form a thread. And since the thickness of the bottom plate of the inside of the weakened line 9 is made thin at the nearby position of the part where a handle is formed and made thick to form a Y-shape along the edge from the rectangular aperture C to the air hole D, the weakened line can be easily cut from the hermetically sealing bottom plate 8 and also a sufficient strength can be kept, the outflow opening can be opened to have a required shape.