Astaxanthin (ATX) has been proven to ameliorate early brain injury (EBI) after experimental subarachnoid hemorrhage (SAH) by modulating cerebral oxidative stress. This study was performed to assess the effect of ATX on the Nrf2-ARE pathway and to explore the underlying molecular mechanisms of antioxidant properties of ATX in EBI after SAH. A total of 96 male SD rats were randomly divided into four groups. Autologous blood was injected into the prechiasmatic cistern of the rat to induce an experimental SAH model. Rats in each group were sacrificed at 24 h after SAH. Expressions of Nrf2 and heme oxygenase-1 (HO-1) were measured by Western blot and immunohistochemistry analysis. The mRNA levels of HO-1, NAD (P) H: quinone oxidoreductase 1 (NQO-1), and glutathione S-transferase-α1 (GST-α1) were determined by real-time polymerase chain reaction (PCR). It was observed that administration of ATX post-SAH could up-regulate the cortical expression of these agents, mediated in the Nrf2-ARE pathway at both pretranscriptional and posttranscriptional levels. Meanwhile, oxidative damage was reduced. Furthermore, ATX treatment significantly attenuated brain edema, blood-brain barrier (BBB) disruption, cellular apoptosis, and neurological dysfunction in SAH models. This study demonstrated that ATX treatment alleviated EBI in SAH model, possibly through activating the Nrf2-ARE pathway by inducing antioxidant and detoxifying enzymes.