Provided is a 1000-series aluminum alloy plate which has high strength applicable to large-size lithium ion battery cases and also has excellent moldability and excellent laser weldability. An aluminum alloy plate produced from a DC cast slab. The aluminum alloy plate has such a chemical composition comprising 0.01 to 0.4 mass % of Si, 0.01 to 0.5 mass % of Fe, 0.002 to 0.3 mass % of Co and a remainder made up by Al and impurities, wherein the content of Cu, which is contained as an impurity, is limited to less than 0.2 mass %. The aluminum alloy plate has a metallic structure in which the number of second phase particles each having an equivalent circle diameter of 3 μm or more is 110 particles/mm2 or more and less than 1000 particles/mm2. A cold-rolled and annealed plate produced from the aluminum alloy plate has an elongation value of 30% or more.