To provide a cap seal made of a resin, sanitary, unnecessary to perform sorting disposal, causing no fold of a side sheet although a resin sheet in which the amount of resin to be used is kept at a low level is used, having less occurrence of wrinkles on a shrink film, and excellent in a finished appearance.

The cap seal is formed with a top face cover 1 having a side sheet 3 which is integrally connected to the circumference of a top sheet 2 made of a resin, and a cylindrical shrink film 4 for covering an outer face of the top face cover 1, leaving a center portion of the top sheet 2. The top sheet 2 is formed into a polygonal shape, and ridges 5 having the same number as that of angles of the polygonal shape are provided on the side sheet 3 in its perpendicular direction. It is preferable that a number of the ridges are in a range of 5-100 ridges.