We propose a new known plaintext attakc of FEAL cipher. Our method differs from previous statistical ones in point of deriving the extended key in a deterministic way. As a result, it is possible to break FEAL-4 with 5 known plaintexts and FEAL-6 with 100 known plaintexts, respectively. Moreover, we show a method to break FEAL-8 with 215 known plaintexts faster than an exhaustive key search.