An aluminum alloy plate includes peritectic elements and Mg. Wherein plate thickness of the plate is represented as t (mm), a range within ±0.01×t from t/2 is represented as a central portion, a range within ±0.01×t from t/4 is represented as a quarter portion, and a range within 0.02×t from a top surface in the plate thickness direction is represented as a superficial portion, concentration of the peritectic elements is such that a concentration difference between in the central portion and in the quarter portion, and a concentration difference between in the central portion and in the superficial portion are 0.04% (mass %) or less. In addition, concentration of the Mg is such that a concentration difference between in the central portion and in the quarter portion, and a concentration difference between in the central portion and in the superficial portion of the plate thickness are 0.4% or less.