Mangrove leaf (Avicennia marina) has a role in wound healing process, but its effect in wound healing in oral mucosa has not been researched yet. This study aimed to prove the effect of A.marina extract against traumatic ulcer and its effective concentration in traumatic ulcer healing. The subjects of this research are 25 wistar rats that were randomized into 5 different groups; K0 control, K1 were given hyaluronic acid, P1 were given extract of A.marina 10%, P2 were given extract of A.marina 20%, and P3 were given extract of A.marina 40%. After the subjects were wounded using amalgam stopper that has been heated before, they were given topical application once daily until seven days. The ulcer diameter was measured at the second day and day 8 using caliper digital. The data, analyzed using Kruskal-Wallis test showed that there’s difference in diameters between two groups (p<0.05). The average diameter differences of traumatic ulcer among rats are K0 = 0.5700 mm , K1 = 0.8380 mm, P1 = 0.7240 mm, P2 = 0.8440 mm, and P3 = 0.9500 mm. It was concluded that A.marina extract of 10%, 20% and 40% concentrations have effect in the healing of traumatic ulcer, and 40% is the most effective concentration against traumatic ulcer.