Free amino acid in ethanol extracts and total amino acid hydrolysates of Coicis semen were analyzed by amino acid autoanalyzer. The sample A (unpolished Coicis Semen) and sample B(polished Coicis Semen) are used in this experiments. The results obtained from this study are as follows: 1) 17 kinds of free amino acid (Asp, Thr, Ser, Glu, Pro, Gly, Ala, Val, Cys, Met, Ileu, Lew, Try, Phe, Lys, His, Arg,) including 7 kinds of essential amino acid (Val, Lew, Ileu, Thr, Lys, Met, Phe,) as human nutrition were identified and quantified but tryptophan. 2) Total free amino acids of sample A is more than about 3 folds that of sample B. 3) The distribution of free amino acids contained in sample A, threonine is the richiest and then comes Ala, Glu, Asp, and Pro, in that order. In sample B, glutamic acid is the richiest and then comes Thr, Asp, Ala, and Gly, in that order. 4) 17 kinds of total amino acid (Asp, Thr, Ser, Glu, Pro, Gly, Ala, Val, Cys, Met, Ileu, Lew, Tyr, Pher, Lys, including 7 kinds of essential amino acid (Val, Leu, Ileu, Thr, Lys, Met, Phe,) in human nutrition except tryptophan were identified and quanified. 5) Total amino acid content of sample A is more than about 1.06 folds that of sample B. 6) Total amino acid content of sample A in acid hydrolysates is more than about 1.06 folds that of sample B in acid hydrolysates. 7) Unknown chromatogram of ethanol extracts and acid hydrolysates of Coicis Semen were identified as Ornitine.