Provided is a constant temperature container capable of largely improving the heat insulating property. A constant temperature container includes: a heat insulating container; a heat insulating lid configured to close the heat insulating container; a box body housed inside the heat insulating container; a box lid configured to close the box body; a phase change material provided on a bottom portion and a wall portion of the box body and the box lid; and a support member provided between the bottom portion of the box body and a bottom portion of the heat insulating container, the support member supporting the box body in such a manner that the wall portion of the box body is separated from a wall portion of the heat insulating container.