A valuable metal collection method of collecting nickel, cobalt, and lithium, valuable metals contained in a positive electrode material of a lithium ion battery, the method comprising: a leaching step of leaching out the valuable metals from a positive-electrode active substance by immersing the positive electrode material in an acidic solution together with a metal having a lower reduction potential than a reduction potential of hydrogen, wherein the metal having a lower reduction potential than a reduction potential of hydrogen is nickel metal obtained from a nickel-metal hydride battery, the method further comprising: a rare earth element removal step, wherein an alkali sulfate is added to the leachate obtained by the leaching step, thereby removing a rare earth element contained in said leachate as a double sulfate and a sulfurizing step, wherein a sulfurizing agent is added to a mother liquor obtained through the rare earth element removal step, and, with adjusting a pH of said mother liquor to 2 to 5, a mixed sulfide of nickel and cobalt is formed, wherein the positive electrode material is immersed in the acidic solution to dissolve the positive-electrode active substance and a positive electrode substrate having the positive-electrode active substance adhering thereto, whereby the valuable metals are leached out from the positive-electrode active substance, and wherein the positive electrode substrate is aluminum foil. a leaching step of leaching out the valuable metals from a positive-electrode active substance by immersing the positive electrode material in an acidic solution together with a metal having a lower reduction potential than a reduction potential of hydrogen, wherein the metal having a lower reduction potential than a reduction potential of hydrogen is nickel metal obtained from a nickel-metal hydride battery, the method further comprising: a rare earth element removal step, wherein an alkali sulfate is added to the leachate obtained by the leaching step, thereby removing a rare earth element contained in said leachate as a double sulfate and a sulfurizing step, wherein a sulfurizing agent is added to a mother liquor obtained through the rare earth element removal step, and, with adjusting a pH of said mother liquor to 2 to 5, a mixed sulfide of nickel and cobalt is formed, wherein the positive electrode material is immersed in the acidic solution to dissolve the positive-electrode active substance and a positive electrode substrate having the positive-electrode active substance adhering thereto, whereby the valuable metals are leached out from the positive-electrode active substance, and wherein the positive electrode substrate is aluminum foil. a rare earth element removal step, wherein an alkali sulfate is added to the leachate obtained by the leaching step, thereby removing a rare earth element contained in said leachate as a double sulfate and a sulfurizing step, wherein a sulfurizing agent is added to a mother liquor obtained through the rare earth element removal step, and, with adjusting a pH of said mother liquor to 2 to 5, a mixed sulfide of nickel and cobalt is formed, wherein the positive electrode material is immersed in the acidic solution to dissolve the positive-electrode active substance and a positive electrode substrate having the positive-electrode active substance adhering thereto, whereby the valuable metals are leached out from the positive-electrode active substance, and wherein the positive electrode substrate is aluminum foil.