Effects of aluminum (Al) on plasma vitellogenin (VTG), alkaline-labile phosphorus (ALPP), calcium (Ca), glutamate pyruvate transaminase (GPT), the hepatosomatic index (HSI), and hepatic Al concentration were examined in estradiol-$17{eta}$ ($E_2$)-administered immature rockfish Sebastes schlegeli. Fish were injected intraperitoneally with $E_2$ (5 mg/kg body weight [BW]) and/or Al (0, 0.1, 1, 5, and 10 mg/kg BW) and plasma and liver samples were extracted 7 days later. After sodium dodecyl sulfate polyacrylamide gel electrophoresis, the relative amount of VTG was determined by integrated optical density. VTG accounted for 23.6% of the total proteins in the control group, but this value decreased with increasing Al administration. Al reduced the concentrations of ALPP and Ca in a concentration-dependent manner and significant reduction occurred at Al concentrations greater than 5 mg/kg. The concentration of GPT increased in a concentration-dependent manner in all Al-administered rockfish. The concentrations of Al in the liver also increased, and HSI was decreased, in a concentration-dependent manner. These results suggest that Al inhibits $E_2$-induced VTG production by being toxic to hepatocytes in marine fish.