Abstract: A cap has a tubular body and a base formed on one end of the tubular body. The cap can be stably stood on a flat object, such that the cap does not need to be held when the needle is inserted into the cap. The user does not need to hold the cap. The user will not be punctured. The safety of disposing of the used syringe can be improved. In addition, the needle can be punched out of the hub and drop through the opening in the cap. The plastic cap and hub does not need to be melted and burned with the needle. The generation of hazardous gas is avoided.