Cap and method for manufacturing cap

A method for manufacturing a cap comprising:

• arranging a molded product including a top plate portion and a skirt portion integrally formed with the top plate portion via an annular and curved corner portion in a first tool including a plurality of first protrusions on an outer peripheral surface thereof, a plurality of large-diameter-portion forming portions adjacent to the first protrusions in an axial direction, and small-diameter-portion forming portions adjacent to the large-diameter-portion forming portions in a circumferential direction;
• and
• forming a plurality of recessed portions, a plurality of small diameter portions, and a plurality of large diameter portions in the skirt portion by relatively rotating the first tool and a second tool including second protrusions arranged between the adjacent first protrusions of the first tool and causing the second protrusions to enter between the adjacent first protrusions, wherein each of the small diameter portions is adjacent to the top plate portion and adjacent to a corresponding locking portion of a plurality of locking portions, and wherein the plurality of locking portions are arranged in a circumferential direction in the skirt portion.