  Interplay between the Mott transition and the multicritical phenomenon of
d-wave superconductivity (SC) and antiferromagnetism (AF) is studied
theoretically. We describe the Mott transition, which is analogous to a
liquid-gas phase transition, in terms of an Ising-type order parameter $\eta$.
We reveal possible mean-field phase diagrams produced by this interplay.
Renormalization group analysis up to one-loop order gives flows of coupling
constants, which in most cases lead to fluctuation-induced first-order phase
transitions even when the SO(5) symmetry exists betwen the SC and AF. Behaviors
of various physical quantities around the Mott critical point are predicted.
Experiments in $\kappa$-(BEDT-TTF)$_2$X are discussed from this viewpoint.
