The amounts of permeation of thiocyanate ion and of thiosulfate ion through gelatin film, polyvinyl alcohol film, gelatin emulsion film, and polyvinyl alcohol emulsion film were determined with analytical method such as Volhard's method, iodimetry, and colorimetry. The results obtained are as follows: 1) The amount of permeation of thiocyanate ion through the films are greater than that of thiosulfate ion. 2) The amount of permeation of ammonium thiosulfate through the gelatin film are larger about 15 to 20 percents than that of sodium thiosulfate. 3) The amount of permeation of ammonium thiosulfate through the gelatin emulsion film did not differ with that of the salt through the polyvinyl alcohol emulsion one. 4) As to the amount of permeation of thiocyanate ion and thiosulfate ion through the non-hardened gelatin film, the ratios of amount of thiocyanate ion permeated were 1.92 in the case of ammonium thiocyanate and 1.16 in the case of sodium thiocyanate after three minutes, 2.08 and 1.81 after five minutes, 4.24 and 3.00 after ten minutes respectively. Here the amount of thiosulfate ion permeated in the case of ammonium thiosulfate is assumed to be one. The ratio for hardened gelatin film was 1:1.8 approximately. 5) The amount of permeation of thiocyanate ion through polyvinyl alcohol (vinylon) film increased in the order, LiSCN < Mg (SCN) ₂ < NaSCN < NH₄SCN < KSCN.