To prevent the oxidization of fry materials by arranging the lower part of an inner pot incorporated with a basket for accepting the fry materials and dipping them in frying oil so as to be inserted to an outer pot and keeping the upper surface of the frying oil in the inner and outer pots at an evacuated atmosphere during producing the fried foods and during evacuation.

The inner pot 2 in which the basket 1 for housing the fry materials A is suspended inside and whose upper opening is closed with a lid 2a is provided and the outer pot 3 is provided so as to involve the lower edge of this inner pot 2 with a gap part 3a. A communicating part 2b communicating the pots 3 and 2 is provided under the pot 2. In addition, an air exhausting means 4 for respectively exhausting air over the frying oil B in the pots 2 and 3 and an air introducing means 5 introducing air to over the oil B are attached and floats 6 are made to float so as to cover upper surface of the oil B. Then during frying work, the means 4 is driven to make pressure-reduced atmosphere to improve the level of the oil B and the materials A are dipped into the oil B.