In this paper, the effect of ductility enhancement on the forming limit of the multilayer metallic sheet Is investigated. Multilayer metallic sheet consists of high-ductility soft material and high-strength hard material, and each constituent material Is layered alternately. The remarkable feature of this metal Is that the constituent hard layer can be elongated beyond its fracture strain. Geometric constraint by the soft layer plays a significant role In enhancing the ductility of the hard layer. This paper deals with this effect In terms of load transfer between the constituent materials. Using the load function of each component, the effect of the ductility enhancement is analyzed quantitatively. The mechanism presented In this paper clearly describes how a multilayer metallic sheet elongates and fractures. Namely, when the constituent soft layer attains to the maximum load, diffuse necking in the soft layer occurs, which immediately trigger the entire fracture of the sheet. To obtain a precise forming limit, the change of work-hardening property along with the above-mentioned mechanism should be treated. Investigations with experimental data verified the effectiveness of this treatment.