Insect-resistant transgenic (Bt-9) rice was generated by inserting the mCry1Ac1 a modified gene from the soil bacterium Bacillus thuringiensis into the genome of a conventional variety of rice (Ilmibyeo). With regard to the potential problems of safety, the non-target organism evaluation is required as an essential element for the environmental risk assessment of genetically modified (GM) crops. For biosafety assessment, we studied the effects on survival of cantor Daphnia magna, a commonly used as a model organism in ecotoxicological studies. D. magna fed on Bt-transgenic rice (Bt-9) and its near non-GM counterparts (Ilmibyeo) grown in the same environment (100% ground rice suspension). The Bt-9 rice was comfirmed to have the insertion of T-DNA and protein expression by the PCR and ELISA analysis. Feeding study showed similar cumulative immobility and abnormal response of Daphnia magna between Bt-9 rice and Ilmibyeo. 48hr-EC50 values of Bt-9 and Ilmi rice showed 4,400 mg/L (95% confidence limits: 3861.01 ~ 5015.01 mg/L) and 5,564mg/L (95% confidence limits: 4780.03 ~ 6476.93 mg/L) respectively. The rice NOEC (No observed effect concentration) value for D. magna was suggested 1,620mg/L. We conclude that the tested Bt-9 and Ilmi similar cumulative immobility for D. magna the widely used model organism. We found out that there is strong possibility that the growth of Bt-9 didn’t affect to non-target insects.