A method of manufacturing a metallic shell for an ignition plug, the metallic shell assuming a tubular form, extending in a direction of an axial line, and having a threaded portion on its outer circumferential surface for threading engagement with a mounting hole of a combustion apparatus, the method comprising: a metallic shell tubular intermediate forming step of forming a metallic shell tubular intermediate which is a metallic shell intermediate having a tubular portion and is to become the metallic shell for an ignition plug, and a rolling step of forming the threaded portion by performing rolling on the metallic shell tubular intermediate by use of rolling dies (D1, D2), and the method being characterized in that the metallic shell tubular intermediate forming step comprises: a first tubular portion forming step of forming a first tubular portion at an end portion of the metallic shell intermediate, and a second tubular portion forming step of forming a second tubular portion at at least a portion of that region of the metallic shell intermediate which differs from the first tubular portion; and in the rolling step, in a condition in which a bearing member is inserted into the metallic shell tubular intermediate for nipping the metallic shell tubular intermediate in cooperation with working surfaces of the rolling dies (D1, D2), rolling is performed simultaneously on at least the first tubular portion and the second tubular portion such that radial eccentricity after the rolling step between a center axis of the first tubular portion and a center axis of the second tubular portion becomes smaller than radial eccentricity before the rolling step between the center axis of the first tubular portion and the center axis of the second tubular portion. a metallic shell tubular intermediate forming step of forming a metallic shell tubular intermediate which is a metallic shell intermediate having a tubular portion and is to become the metallic shell for an ignition plug, and a rolling step of forming the threaded portion by performing rolling on the metallic shell tubular intermediate by use of rolling dies (D1, D2), and the method being characterized in that the metallic shell tubular intermediate forming step comprises: a first tubular portion forming step of forming a first tubular portion at an end portion of the metallic shell intermediate, and a second tubular portion forming step of forming a second tubular portion at at least a portion of that region of the metallic shell intermediate which differs from the first tubular portion; and in the rolling step, in a condition in which a bearing member is inserted into the metallic shell tubular intermediate for nipping the metallic shell tubular intermediate in cooperation with working surfaces of the rolling dies (D1, D2), rolling is performed simultaneously on at least the first tubular portion and the second tubular portion such that radial eccentricity after the rolling step between a center axis of the first tubular portion and a center axis of the second tubular portion becomes smaller than radial eccentricity before the rolling step between the center axis of the first tubular portion and the center axis of the second tubular portion. a first tubular portion forming step of forming a first tubular portion at an end portion of the metallic shell intermediate, and a second tubular portion forming step of forming a second tubular portion at at least a portion of that region of the metallic shell intermediate which differs from the first tubular portion; and in the rolling step, in a condition in which a bearing member is inserted into the metallic shell tubular intermediate for nipping the metallic shell tubular intermediate in cooperation with working surfaces of the rolling dies (D1, D2), rolling is performed simultaneously on at least the first tubular portion and the second tubular portion such that radial eccentricity after the rolling step between a center axis of the first tubular portion and a center axis of the second tubular portion becomes smaller than radial eccentricity before the rolling step between the center axis of the first tubular portion and the center axis of the second tubular portion.