To provide an electrolyzer for molten metal chloride capable of suppressing the reduction in current efficiency caused by depositions at a high level.

The device is provided with an electrolytic cell and a partition sagged from the upper part of the electrolytic cell. A storage chamber and an electrolytic chamber for produced metal are formed on both the sides with the partition sandwiched. The side of the electrolytic chamber in the upper part of the electrolytic cell is provided with a gas exhaust nozzle. The electrolytic chamber is provided with a cathode and an anode. The side of the storage chamber in the upper part of the electrolytic cell is provided with a cover. A heat exchanger having two conduits and a plurality of branch tubes elongating in the horizontal direction from either to the other in the two conduit tubes and elongating in the vertical direction on the side of the storage chamber at the inside of the electrolytic cell so as to pass through the cover from the outside is provided. At least one part among the upper part, lower part and therebetween in the plurality of branch tubes is provided with an impurity collection member parallel to the branch tubes.