We have investigated exotic properties in strongly correlated electron systems under high pressure and have prepared high quality specimens. Pressure is a useful external parameter to tune interactions in these systems without breaking a translational symmetry. In order to study these exotic properties, we perform not only magnetization measurement and Mossbauer spectroscopy but also state-of-the-art spectroscopic techniques like nuclear resonant scattering utilizing synchrotron radiation under multi-extreme conditions such as low temperature, high pressure and high magnetic field.