Reinforced metal core board and electric connection box having the same

A metal core board which is used for an electric connection box, comprising:

• a plurality of core metal plates to be laminated that are separated in a vertical direction;
• insulation resin filled between each of the plurality of core metal plates;
• and
• a slit formed in at least one of the plurality of core metal plates so as to divide the core metal plate to a plurality of separate plates and being filled with the insulation resin therebetween, wherein the slit is disposed to entirely overlap, at a corresponding lateral position, a region of another vertically separated core metal plate that defines a contiguous sheet of metal so that each contiguous sheet of metal at the corresponding lateral position overlaps at least one slit, and wherein the slit is not formed in at least one of the plurality of core metal plates, thereby a part of the core metal plate having a weak strength due to formation of the slit is reinforced.