A storage box includes a wall including: a packaging member; and a heat transfer body and a cold storage agent that are stored in the packaging member. The cold storage agent is disposed closer to an outer surface of the storage box than the heat transfer body is. Consequently, a chill from the cold storage agent spreads over the heat transfer body, and the chill is transferred to an inside of the storage box through the heat transfer body. Thus, a temperature can be more homogeneously maintained in the storage box.