A new method of freeze concentration with ice-lining has been developed, which enables concentration of the solution to proceed only through the growth of an ice layer preformed on the inner wall of a agitated vessel crystallizer with cooling jacket. From the measurements of concentration and volume of the residual solution during the freezing process of cephalosporin C sodium solution, it is revealed that this method is superior for recovery of high concentrate compared with the simple method without ice-lining. The apparent partition coefficient of the solute was defined as the ratio of its concentration in the ice formed to that in the residual solution. The experimental results showed that the partition coefficient decreases with decreasing concentration of feed solution and the difference between the brine temperature and the freezing point of the feed solution, as well as with increasing impeller speed. In addition, it has been confirmed that this method results in little degradation to the substance contained in the concentrate compared with the ordinary method by evaporation.