  By using the standard perturbation theory we study the mass as well as
$\theta$ parameter dependence of the Seiberg-Witten theory with $SU(2)$ gauge
group, supplemented with a $N=1$ supersymmetric as well as a smaller
nonsupersymmetric (e.g.) gaugino mass. Confinement persists at all values of
the bare vacuum parameter $\theta_{ph}$; as it is varied there is however a
phase transition at $\theta_{ph} =-\pi, \pi, 3\pi, \ldots$. At these values of
$\theta_{ph}$ the vacuum is doubly degenerate and CP invariance is
spontaneously broken \`a la Dashen. Due to the instanton-induced
renormalization effect the low energy effective $\theta$ parameter remains
small irrespectively of $\theta_{ph}$ as long as the gaugino mass is
sufficiently small.
