PURPOSE: A powdery adsorbent is added to fry oil, they are stirred under heating to effect adsorption and the adsorbent is removed, thus eliminating the deteriorated parts in the fry oil.

CONSTITUTION: The tank 2 for adsorption and filtration is made narrower in diameter at the bottom than at the upper part and fitted to the upper opening 4 of larger diameter of the receiver 1 for the purified oil. A plurality of filtering pores 8 are perforated on at least the bottom of the tank 2 and on oil purification, a filtering membrane 9 capable of stopping the powdery adsobent is placed on the inside of the tank 2. Used edible oil 10 and a granular or pulverous adsorbent 11 such as active clay or activated carbon black are charged in the tank 2 to effect adsorption and filtration. The upper cover is provided with a stirrer 12, which stirrs the oil. When necessary, an immersion heater 14 is placed on the bottom of the tank 2.