  The drastic changes of Fermi surfaces as well as transport anomalies near
P=Pc~2.35 GPa in CeRhIn5 are explained theoretically from the viewpoint of
sharp valence change of Ce. It is pointed out that the key mechanism is the
interplay of magnetic order and Ce-valence fluctuations. It is shown that the
antiferromagnetic state with "small" Fermi surfaces changes to the paramagnetic
state with "large" Fermi surfaces with huge enhancement of effective mass of
electrons with keeping finite c-f hybridization. This naturally explains the de
Haas-van Alphen measurement and also the transport anomalies of T-linear
resistivity emerging simultaneously with the residual resistivity peak at P=Pc
in CeRhIn5.
