The present invention provides a method for performing regeneration of a decolorization capacity of waste clay that has been used for purification of fats and oils, and production of a thermally recyclable compound as a biofuel from oily ingredients in the waste clay at the same time in a convenient manner. That is, a method for producing purified fats and oils of the invention includes: a method for producing regenerated clay including the steps of mixing waste clay that has been used for purification of fats and oils, lower alcohol, and an acidic catalyst; and performing extraction of oily ingredients from the waste clay, and an esterification reaction between the fats and oils and/or a free fatty acid in the oily ingredients and the lower alcohol at the same time so as to regenerate a decolorization capacity of the waste clay; regenerated clay that is produced by the method for producing the regenerated clay; and a process of decolorizing the fats and oils using the regenerated clay.