Synthetic resin cap

Abstract

[Object] To provide a synthetic resin cap of a structure that is further improved in convenience when drinking while suppressing falling or loss of the cap when a container is opened. [Solving Means] A synthetic resin cap as a specific example of the present invention has a tamper-evident band to be fitted on an outer peripheral surface of a container mouth portion of a container, and a cap main body having a skirt wall and a top plate, and including, in the skirt wall, a fixing rib coupled with the tamper-evident band via a weakened portion and a strap portion and extending to a radially outer side of the skirt wall. The fixing rib is formed from a first inclined portion that flares downwards, and a protrusion portion that is disposed below the first inclined portion. When the container is opened, a side surface of the container mouth portion and the protrusion portion come into contact with each other, and an upper surface of a laterally extending portion, the laterally extending portion being disposed below the container mouth portion and extending in a radial direction, and the top plate come into contact with each other, thereby maintaining a posture of the cap main body when the container is opened.