  We investigated the effect of magnetic field on the highly correlated metal
near the Mott transition in the quasi-two-dimensional layered organic
conductor, $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl, by the resistance
measurements under control of temperature, pressure, and magnetic field. It was
demonstrated that the marginal metallic phase near the Mott transition is
susceptible to the field-induced localization transition of the first order, as
was predicted theoretically. The thermodynamic consideration of the present
results gives a conceptual pressure-field phase diagram of the Mott transition
at low temperatures.
