  We point out that a background torsion field will produce an effective
potential to the $K$ and $\bar{K}$ with opposite signs. This allows us to
constrain the background torsion field from the $K_L$ and $K_S$ mass
difference, CPT violating $K^\circ$ and $\bar{K^\circ}$ mass difference and the
CP violating quantities $\epsilon$ and $\eta_{+-}$. The most stringent bound on
the cosmological background torsion $< T^0 > < 10^{-25}$ GeV comes from the
direct measurement of the CPT violation.
