Supercritical and subcritical fluid device, solvent extraction and separation method, and method for producing product

A supercritical and subcritical fluid device comprising:

• a extraction and separation column;
• a first liquid feeding part connected to a lower portion of the extraction and separation column via a first flow path and configured to supply a mobile phase serving as a supercritical fluid;
• a second liquid feeding part connected to an upper portion of the extraction and separation column via a second flow path and configured to supply a separation target;
• a first back pressure adjustment mechanism connected to the lower portion of the extraction and separation column via a third flow path and configured to set an inside of the extraction and separation column to a first pressurized state in which the mobile phase is maintained in a supercritical fluid state;
• a second back pressure adjustment mechanism connected to the upper portion of the extraction and separation column via a fourth flow path and configured to set the inside of the extraction and separation column to a second pressurized state in which the mobile phase is maintained in a supercritical fluid state;
• and
• a control unit configured to control the first back pressure adjustment mechanism and the second back pressure adjustment mechanism, wherein
• the control unit controls the first back pressure adjustment mechanism and the second back pressure adjustment mechanism such that the second pressurized state is reduced by a predetermined pressure difference with respect to the first pressurized state.