Container lid having oxygen shielding properties

This container lid having oxygen shielding properties is provided with a high-density polyethylene cap shell having a skirt section (7) and a top plate section (5) to which an inner ring (9) for forming a tight seal with the inside surface of a container mouth is provided, and an in-shell molded body (3) provided to a portion of the inside surface of the top plate section that is surrounded by the inner ring (9), the in-shell molded body (3) comprising an oxygen-shielding primary molded body (3a) formed by in-shell molding on the inside surface of the top plate section, and a secondary molded body (3b) which covers the primary molded body (3a) and is melt-fixed to the inside surface of the top plate section at a peripheral edge of the primary molded body (3a) by in-shell molding, and a resin composition including straight-chain low-density polyethylene and having a melt flow rate of 1-10 g/10 minutes at 190°C, a density of 0.900-0.920 g/cm3, and a nominal tensile strain at break of at least 400% as specified by JIS K-6922-2 being used in the secondary molded body (3b).