SYNTHETIC RESIN CONTAINER LID

A cap-type synthetic resin container lid (2), which can be removed sufficiently easily from a mouth-neck section (38) of a container without requiring great force and, even after removal from the mouth-neck section (38) of the container, continues to be kept integral without being partly separated to form a scrap piece, is provided. The container lid (2) includes thin-walled inversion pieces (18) arranged at intervals in the circumferential direction and extending upward beyond a top panel wall (4) from the lower ends of the thin-walled inversion pieces, the lower ends being connected to the outer peripheral surface of a skirt wall (6) or to the boundary part between the outer peripheral surface of the skirt wall (6) and the upper surface of the top panel wall (4); a restraint wall (20) connected to the upper ends of the thin-walled inversion pieces (18) and having a specific site (22) in the circumferential direction, the specific site being either split, or being defined by a breakable weakened section (24); and an operating section (30) connected to the outer peripheral surface of the skirt wall (6) via a connecting piece (28) extending out radially from the outer peripheral surface of the skirt wall (6) at a position in alignment with the specific site (22). Locked projections (26) and locking projections (36) are disposed in the restraint wall (20) and the connecting piece (28), respectively, to collaborate in restricting the expansion of the restraint wall (20).