  We investigate geometrical structures and low-energy theorems of N=1
supersymmetric nonlinear sigma models in four dimensions. When a global
symmetry spontaneously breaks down to its subgroup, the low-energy effective
Lagrangian of massless particles is described by a supersymmetric nonlinear
sigma model whose target manifold is parametrized by Nambu-Goldstone (NG)
bosons and quasi-NG (QNG) bosons. The unbroken symmetry changes at each point
in the target manifold and some QNG bosons change to NG bosons when unbroken
symmetry become smaller. The QNG-NG change and their interpretation is shown in
a simple example, the O(N) model. We investigate low-energy theorems at general
points.
