A can body manufacturing method, in which a bottomed cylindrical long cup is shaped from a metal material, in which a printed decoration is then applied to the outer face of a cylindrical trunk portion of the long cup, and in which one of the end sides of the long cup is then shaped into a sloped shoulder portion which is diametrically reduced toward the leading end side: wherein the printed decoration is printed on the outer face of the cylindrical trunk portion of the long cup to the portion to be shaped into the shoulder portion at a subsequent treatment, and wherein the pattern or letter of the printed decoration applied to the portion to be shaped into the shoulder portion is distorted to be wider in the upward direction, in comparison with a final desired figure.