Objectives : This study was performed to evaluate the neuroprotective effect of water extracts from Thujae Semen(TSW) in PC12 cells. Methods : We performed 2,2-diphenyl-2-picrylhydrazyl(DPPH) radical scavenging assay, 2,2-azinobis- (3-ethyl-benzothiazoline-6-sulfonic acid(ABTS) cation scavenging assay, and determination of total polyphenolic content to examine the antioxidant effects of TSW. We also carried out 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay(MTT), reactve oxygen species(ROS) assay, and nitric oxide(NO) assay to examine neuroprotective effects against 6-hydroxydopamine(6-OHDA) in PC12 cells. Results : TSW showed $IC_{50}$ values of 404.3 and 219.9 ${mu}g/mL$ in DPPH and in ABTS assays, respectively. TSW showed 9.74 ${mu}g/mL$ of total polyphenol contents. TSW incresed cell viability in a dose dependent manner and it showed protective effect against 6-OHDA neurotoxicity at the concentration of 25-200 ${mu}g/mL$. Moreover, it recovered 6-OHDA induced cell death at the same concentrations. The extract showed a dose dependent reduction of ROS and NO generation by 6-OHDA. Conclusions : We concluded that TSW has neuroprotective effect against 6-OHDA-induced toxicity in PC12 cells through ROS and NO inhibition.