PROBLEM TO BE SOLVED: To provide a molten core holding device capable of effectively cooling a core melt and preventing radioactive materials generated from the core melt from spreading to the outside, in a case that a severe accident such as a core meltdown happens to occur, and a nuclear reactor containment including the same.SOLUTION: A molten core holding device 20 placed in the lower side of a nuclear reactor pressure vessel 4 comprises a cooling plate 21 that is formed in a wavy shape in cross-section view and whose at least one surface comes into contact with cooling water. Thus, in a case that a severe accident happens to occur such that a core melt D drops from the nuclear reactor pressure vessel 4, a heat transfer area of the cooling plate 21 can be increased to effectively cool the core melt D.
