An isothermal container includes: a vacuum heat insulating container; a vacuum heat insulating lid configured to close the vacuum heat insulating container; a body protection case, and a lid outer protection case and lid inner protection case that cover outside of the vacuum heat insulating container and outside of the vacuum heat insulating lid, respectively; a box body housed inside the vacuum heat insulating container; a box lid configured to close the box body; and a cold storage agent provided on a bottom portion and a wall portion of the box body and the box lid. Outer and inner cover materials are joined together at faces facing the vacuum heat insulating lid among faces constituting the wall portion of the vacuum heat insulating container. A joined part of the materials is located inside the body protection case without being exposed to the outer surface of the body protection case.