The permeability of a porous medium in a state of solidification saturated with NaCl-aqueous solution was measured by a transient method, with a varying volume fraction of liquid phase chi, an initial concentration of solution C-i, and a super-cooling degree : of the solution just before start of solidification T-sc. From the results of measurement, it was shown that the permeability was proportional to the nth power function of chi The influence of C-i and T-sc on the permeability was clarified. An empirical equation of the permeability was obtained as a function of chi, C-i and T-sc.