In order to establish methods of potato processing for mixed cooking with rice as main diet, treatment for polyphenol oxidase inactivation in potato tissues, and safety in regard to sanitation were studied. The results were summarized as follows: 1. Cut potato granule which were blanched in boiling water are practical and best in color within 3∼6 minutes dipping. 2. Dipping treatment of potato granules in a saline solution is not pratical because of the resulting color and saline taste. 3. Dipping treatment of potato granules in a boiling saline solution is not practical because of residual salt. 4. Dipping treatment of potato granules in low concentration of hydrochloric acid solution is not effective in color changes but dipping treatment from 0.1N concentration for 4-7.0 minutes to 0.5N concentration for 1∼10minutes shows good effects. 5. Dipping treatment in boiling hydrochloric acid solution of 0.04-0.068N concentration for 3-5 minutes dipping is practical for its resulting color, 6. Dipping treatments in 0. 05% of K₂S₂O_5 solution for 50∼60 minutes and in 0.06% for 40∼60 minutes and 0.065% for 10∼60 minutes shows a small palatability in color but its boiled potato granules shows good color 7. Treatments for any time in 0.01∼0.03% of boiling K₂S₂O_5 solution after predipping in its cold solution for longer time than 30minutes show effective in the color and palatability of the potato granules and their cooked ones 8. From the view of food sanitation, dipping treatment of the potato granules in the solution of K₂S₂O_5 is safe because of the few residual amount of SO₂. 9. All the methods of treatment that potato granules are dipped for any time at 0.01%of K₂S₂O_5 solution are safe from the view of food sanitation. At 0.03 of K₂S₂O_5solution, nothing but the methods of treatment that they are dipped within 30 minutes and boiled within 4 minutes are safe.