  Impacts on new physics search from $\bbbar, \kkbar$ mixings and the rare
decay $\kplusdecay$ are discussed. We show that, in a certain class of new
physics models, the extra contributions to those processes can be parametrized
by its ratio to the standard model (SM) contribution with the common CKM
factors. We introduce two ratios to measure the new physics contributions,
$R_1$ for $\xd$ and $\ek$ parameters, and $R_2$ for $\kplusdecay$ decay. Then,
the experimentally allowed region for the new physics contributions can be
given in terms of $R_1, R_2$ and the CP violating phase $\delta$ of the CKM
matrix. We find constraints on $R_1$ and $\cosd$ by taking account of current
experimental data and theoretical uncertainties on $\bbbar$ and $\kkbar$
mixings. We also study impacts of future improved measurements on
($R_1,R_2,\cosd$) basis. As typical examples of new physics models, we examine
contributions to those processes in the minimal supersymmetric SM and the two
Higgs doublet model.
