A base plate and load beam for an HG assembly are formed in series, stacked, and transferred by a transfer system in the form of the stacked-layer series to undergo the necessary assembly processes such as layer joining, slider attachment, and electrical connections between the terminals thereon. The base plate structure comprises a band portion having conveying holes and positioning holes formed at a predetermined pith respectively in a longitudinal direction. A plurality of the base plates are disposed via connecting portions integrally formed at a predetermined pitch at edges on one side of the band portion.