Free amino acids in water extracts and total amino acids in hydrolystates of Deer Horn were analyzed by amino acid autoanalyzer (Technicon PNC-1 Type). The results obtained from this study are as follows ; 1) 17 kinds of amino acid, including 7 kinds of essential amino acid in human nutrition except tryptophan were identified and quantified. 2) Of all free amino acid contained in water extract, glutamic acid is the richest, and then comes Ala, Gly, Leu, Lys, valin in that order. Of all total amino acid which are closely related with nutritional valuation glycin is the richest, and then comes Glu, Lys, Ala, Leu, Ala, Pro, in that order. 3) Besides 17 kinds of amino acid, one kinds of unknown amino acid are found in water extracts and hydrolysates.