A method for manufacturing a springback-reduced part formed by performing a springback reduction on a press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155), which is formed by a press forming of a blank sheet (28, 41, 71, 103, 133) made of a metal sheet, wherein the springback-reduced part is formed by: setting each element of an analytic model (23, 101, 131) of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) to a stressed state that causes a springback; performing an optimization analysis for shape to detect a portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) that highly contributes to a rigidity thereof; applying a rigidity improving means on a specific portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) on a basis of the detected portion; and performing the press forming, the method comprising: an analytic model forming step for forming an analytic model (23, 101, 131) of a press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) with plane elements and/or solid elements; a stressed-state setting step for setting each of the elements of the analytic model (23, 101, 131) to a stressed state that causes a springback; characterized by a rigidity-contributable-portion detecting step for performing an optimization analysis for shape on the analytic model (23, 101, 131) with the elements set to the stressed state in the stressed-state setting step to detect a portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) that highly contributes to the rigidity thereof; a rigidity improving step for performing a rigidity improving method on a specific portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) on a basis of the portion detected in the rigidity-contributable-portion detecting step; and a press-forming step for performing a press forming on the blank sheet such that a means for improving the rigidity is applied on a specific portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) on the basis of the detected portion. setting each element of an analytic model (23, 101, 131) of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) to a stressed state that causes a springback; performing an optimization analysis for shape to detect a portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) that highly contributes to a rigidity thereof; applying a rigidity improving means on a specific portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) on a basis of the detected portion; and performing the press forming, the method comprising: an analytic model forming step for forming an analytic model (23, 101, 131) of a press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) with plane elements and/or solid elements; a stressed-state setting step for setting each of the elements of the analytic model (23, 101, 131) to a stressed state that causes a springback; characterized by a rigidity-contributable-portion detecting step for performing an optimization analysis for shape on the analytic model (23, 101, 131) with the elements set to the stressed state in the stressed-state setting step to detect a portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) that highly contributes to the rigidity thereof; a rigidity improving step for performing a rigidity improving method on a specific portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) on a basis of the portion detected in the rigidity-contributable-portion detecting step; and a press-forming step for performing a press forming on the blank sheet such that a means for improving the rigidity is applied on a specific portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) on the basis of the detected portion. an analytic model forming step for forming an analytic model (23, 101, 131) of a press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) with plane elements and/or solid elements; a stressed-state setting step for setting each of the elements of the analytic model (23, 101, 131) to a stressed state that causes a springback; characterized by a rigidity-contributable-portion detecting step for performing an optimization analysis for shape on the analytic model (23, 101, 131) with the elements set to the stressed state in the stressed-state setting step to detect a portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) that highly contributes to the rigidity thereof; a rigidity improving step for performing a rigidity improving method on a specific portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) on a basis of the portion detected in the rigidity-contributable-portion detecting step; and a press-forming step for performing a press forming on the blank sheet such that a means for improving the rigidity is applied on a specific portion of the press-formed part (29, 33, 77, 85, 95, 109, 115, 125, 139, 145, 155) on the basis of the detected portion.