A syringe needle cap (10) is filled to the tip of the barrel (21) of a prefilled syringe (20). And the tip of a syringe needle (22) is stuck into a needlepoint receiving section (12A) on the inner layer portion (12) of the syringe needle cap (10). The outer circumference of a needle section (21B) on the tip of the prefilled syringe (20) is closely attached to a joining section (12B) on the inner layer portion (12) of the syringe needle cap (10), thereby securely sealing the inner space within the syringe needle cap (10) which covers the syringe needle (22). The outer layer portion (11) functioning as the cap main body of the syringe needle cap (10) is formed from a transparent resin, and the inner layer portion (12) is formed from a transparent elastomer as the interior material. As a consequence, the entire syringe needle (22) of the prefilled syringe (20), including the tip section, can be seen from the outside.
