We investigated the proper dietary protein and lipid levels for growth and body composition of juvenile sea cucumber Stichopus japonicus. Three replicate groups of the sea cucumber(average weight of 1.1 g) were fed the experimental diets containing different levels of protein(10, 20, 30 and 40%) and lipid(3, 7 and 11%) for 10 weeks. At the end of the feeding trial, survival of each group was over 87%, and there was no significant difference among the groups. Weight gain and specific growth rate(SGR) of sea cucumber were significantly affected by dietary protein(P<0.005) and lipid levels(P<0.001). The highest weight gain and SGR were observed when sea cucumber fed the diet containing 30% protein with 3% lipid(P<0.05). Weight gain and SGR of the sea cucumber fed the diet containing 3% lipid were higher than the other groups at the same protein level except for 40% protein group(P<0.05). Protein content of the sea cucumber fed the diet containing 30% protein with 3% lipid was significantly (P<0.05) higher than those fed 20% protein diets with 7% or 11% lipids and 10% protein diet with 7% lipid. Moisture, lipid and ash contents of the whole body were not significantly different among the groups. Fatty acid compositions such as linoleic acid, EPA(20:5n-3) and DHA(22:6n-3) of the whole body were affected by those of dietary lipid sources. The results of this study indicate that the diet containing 30% protein and 3% lipid is optimal for growth of juvenile sea cucumber.