  The two dimensional supersymmetric CP(N-1) model has a striking similarity to
the N=2 supersymmetric gauge theory in four dimensions. The BPS mass formula
and the curve of the marginal stability (CMS), which exist in the four
dimensional gauge theory, appears in this two dimensional CP(N-1) model. These
two quntities are derived by a one-dimensional n-vector spin model in the large
n limit for the N=2 case. This mapping is further investigated at the critical
point. An application of the study of the BPS mass formula is proposed to the
phenomena of the spin and charge separations in the Higgs phase.
