This Study was tarried out to investigate the relationship ACE inhibitory activity and degradations of sulfur containing materials in Dolsan leaf mustard juice (DLMJ). The changes of sulfur containing materials which were treated with autolysis, myrosinase, ascorbate and papain were studied, as well as the changes of ACE inhibitory activity in DLMJ. At $37^{circ}C$, sulfur contain-ing materials by autolysis decreased most rapidly from $0.43\%$ to $0.13\%$ in the second day. Conversely. ACE inhibitory activity increased most from $66\%$ to $87\%$. in the second day at $37^{circ}C$. As myrosinase concentrations increased more, sulfur containing materials in DLMJ decreased more. The ACE inhibitory activities at 0, 0.5, 1, 2, and 4 Units of myrosinase for 240 min later were 70, 74, 75, 82, and $85\%$, respectively. At 1 mM ascorbate. concentrations of Sulfur containing materials in DLMJ decreased more significantly on the second day than on the other days. At 1 mM ascorbate for 6 days, ACE Inhibitory activity reached a maximum of about $92\%$. And, an increase of papain concentration was noted in accordance with a decreased sulfur containing materials. The maximum rate of AEC inhibitory activity at control, 3, 6, and 12 Units of papains treatments was shown as 70, 70, 75, and $78\%$ at 60 min, respectively. These results suggested that the degradation of sulfur containing materials led to the increase of ACE inhibitory activity. Consequently, it was suggested that ACE inhibiting was significantly related to the degradatives of sulfur containing materials.