<p>A process which comprises using two kinds of solvents which are different in specific gravity and take the form of a homogeneous or phase-separated mixture depending on temperature and a reactor (2) equipped with a temperature control unit which can keep the upper and lower zones of the reactor (2) at such temperatures that the solvents take the form of a phase-separated mixture and the intermediate zone thereof at such a temperature that the solvents take the form of a homogeneous mixture and feeding continuously a solution of the first raw material (X) in a light solvent having a smaller specific gravity to the bottom of the reactor (2) through a light solvent feeder (5L) and a solution of the second raw material (Y) in a heavy solvent having a larger specific gravity to the top of the reactor (2) through a heavy solvent feeder (5H) to conduct a reaction of the raw material (X) with the raw material (Y) in the intermediate zone of the reactor (2) in a homogeneous mixture of the solvents and by which a product (Z) soluble in only one of the solvents can be continuously produced and a solution of the product (Z) in the solvent can be recovered from a recovery port (12L).</p>
