An enzyme preparation with affinity to a lysine column was detected from a DEAE-cellulose-adsorbed preparation of human seminal plasma containing plasminogen and plasmin. Two kinds of trypsin-like acidic arginine amidase activity with different affinity to lima bean trypsin inhibitor (LBTI) and aprotinin affinity column were detected from the DEAE-cellulose-adsorbed preparation after treatment of the lysine column. Two kinds of trypsin-like basic arginine amidase activity were also separated by the above-mentioned affinity adsorptions from a CM-cellulose-adsorbed preparation of human seminal plasma. The effect of calcium chloride on these two enzymes was different from human acrosin.