This study investigated the effect of dietary arachidonic acid (ARA, 20:4n-6) on final maturation, spawning performance and composition of the gonad of black sea urchin (Diadema setosum). Four different dietary ARA levels of 0.3 g/kg (Control diet), 1.4 g/ kg (ARA 1.4), 2.5 g/kg (ARA 2.5) and 3.7 g/kg (ARA 3.7) were prepared and tested in this feeding trial for 90 days. The result showed that growth in terms of weight was not relatively affected by dietary ARA. Gonadosomatic Index (GSI) of animals were gradually increased in all the diets throughout the trial. The highest GSI level (25.7 ± 3.16%) was observed in animals fed with the diet ARA 1.4. ARA content in the gonad proportionally increased with dietary ARA levels. The highest larval survival rate (85.5 ± 5.67%) was found in diet ARA 2.5. The results of this study indicate that ARA plays an important role in the reproduction functions of black sea urchin and supplementing an appropriate level of ARA in the broodstock diet could induce the final maturation and improve reproduction of black sea urchin, but a higher level of ARA (3.7 g/kg) seems to have a negative effect on both growth rate and GSI.