STEEL PLATE

Provided is a steel plate that has high strength and has excellent cryogenic toughness uniformly in the steel plate regardless of the thickness. A steel plate comprises a chemical composition containing, in mass %, C: 0.01% to 0.15%, Si: 0.01% to 0.50%, Mn: 0.05% to 0.60%, Ni: 6.0% to 7.5%, Cr: 0.01% to 1.00%, Mo: 0.05% to 0.50%, P: 0.03% or less, S: 0.005% or less, and N: 0.0010% to 0.0080%, with a balance consisting of Fe and inevitable impurities, wherein at a position of ¼×t, a decrease ratio of an amount of retained γ between before and after deep cooling treatment at −196° C. is less than 5 vol % and the amount of retained γ after the deep cooling treatment is 0.5 vol % or more.