A heat exchanging apparatus comprising: a boxy case open upward; and a heat exchange unit having a heat transfer medium circulation pipe installed at least in part in the case, wherein the heat exchanging apparatus performs heat exchange between heated fluid guided into the case and heat transfer medium circulating in the heat transfer medium circulation pipe, wherein the heat exchanging apparatus is a falling liquid film type for exchanging heat with the heat transfer medium circulating in the heat transfer medium circulation pipe while dropping heated fluid from an opening of the case open upward into the case so as to be distributed and flown down in a liquid film form following an outer surface of the heat transfer medium circulation pipe, wherein the case comprises: an opening section provided on a sidewall of the case; and a plate-like lid member for opening and closing the opening section, characterized in that the heat transfer medium circulation pipe of the heat exchange unit has a heat exchange section wound in a spiral, wherein the heat exchange section is fixed to an inner surface of the lid member using a frame body formed by combining bar-like members, wherein both ends (32a, 32b) of the heat transfer medium circulation pipe penetrate the lid member to project outside the case, and wherein when the lid member is at a position where the opening is closed, the heat exchange section of the heat transfer medium circulation pipe is housed fixedly in the case and when the lid member is at a position where the opening is open, the heat exchange section of the heat transfer medium circulation pipe is withdrawn out of the case. a boxy case open upward; and a heat exchange unit having a heat transfer medium circulation pipe installed at least in part in the case, wherein the heat exchanging apparatus performs heat exchange between heated fluid guided into the case and heat transfer medium circulating in the heat transfer medium circulation pipe, wherein the heat exchanging apparatus is a falling liquid film type for exchanging heat with the heat transfer medium circulating in the heat transfer medium circulation pipe while dropping heated fluid from an opening of the case open upward into the case so as to be distributed and flown down in a liquid film form following an outer surface of the heat transfer medium circulation pipe, wherein the case comprises: an opening section provided on a sidewall of the case; and a plate-like lid member for opening and closing the opening section, characterized in that the heat transfer medium circulation pipe of the heat exchange unit has a heat exchange section wound in a spiral, wherein the heat exchange section is fixed to an inner surface of the lid member using a frame body formed by combining bar-like members, wherein both ends (32a, 32b) of the heat transfer medium circulation pipe penetrate the lid member to project outside the case, and wherein when the lid member is at a position where the opening is closed, the heat exchange section of the heat transfer medium circulation pipe is housed fixedly in the case and when the lid member is at a position where the opening is open, the heat exchange section of the heat transfer medium circulation pipe is withdrawn out of the case.