A very highly concentrated solution is obtained in a single cycle of operation. In the solution separating apparatus, the solution is atomized into the mists to be mixed with the carrier gas, the carrier gas containing such atomized mists is transferred to the collection unit 3, and the collection unit 3 is so constructed and arranged that a specific target substance is separated and collected from the atomized mist component. The solution separating apparatus allows the mist component, by means of the carrier gas, to be in contact with the molecular sieving adsorbent 4 having a molecularly sieving capability of adsorbing the adsorbable component contained in the mist component so as to be separated from the mist component. The non-adsorbable component which is not adsorbed into the molecular sieving adsorbent 4 is separated from the mist component contained in the carrier gas in which the adsorbable component is separated, so that the target substance is separated from the carrier gas.