To provide a bag containing a cold insulator capable of being mounted to a safety helmet, cooling heat insulation liquid by a latent heat effect and keeping cold air.

Relating to this bag 7 containing the cold insulator for which waste styrene foam thin pieces are mixed in waste edible oil, the waste edible oil is filtered by activated carbon or the like, impurities are removed, it is heated and sterilized and the appropriate amount of an antiseptic such as salicylate or the like is added. At the time of adding thin pieces for which the waste styrene foam is made porous and high molecular absorption polymer and ionizing, freezing and solidifying water or other liquid with excellent heat exchangeability, the amount for not becoming too hard is added and it is gelatinized, filled in the bag of a two-layer structure, frozen, solidified and used.