While a compression part (B1) in a bottom wall part of a cup-shaped workpiece (B) is compressed by an inner punch (11) and an inner die (14) and moved in a direction to get away from an intermediate die (15), the inner die (14) is pushed toward the inner punch (11); and a compression part (B2) being an outer end portion in a radial direction of the workpiece (B) is compressed by an outer punch (13) and an outer die (16) and moved in an direction to approach the intermediate die (15), to thereby suppress the workpiece (B) in the compression part (B2) from material-flowing in a direction to get away from a central axis (10), whereby thickness reduction processing of the compression part (B1) and thickness increase processing of a vertical wall part (B3) of the workpiece (B) sandwiched by an intermediate punch (12) and the inner die (15) and a vertical wall part (B4) of the workpiece (B) sandwiched by the intermediate punch (12) and an outer die (16) are performed.