||There are many research reports about the safety of the nanomaterials inside of the human body. However, the embryotoxicity risk of nano material is still not clear. Since numerous nanomaterials are currently being developed, a method for testing embryotoxicity in vitro in a speedy, effective, and precise manner is needed. In 1997. Spielmann et al. developed the embryonic stem cell test (EST), which is an in vitro embryotoxicity test method that can be used to estimate the risk of embryotoxicity of chemical substances relatively quickly compared to the conventional methods that involve animal experiments. The EST has been evaluated in a formal validation study funded by the ECVAM (European Centre for the Validation of Alternative Methods) in which two other in vitro embryotoxicity tests (micromass test, whole embryo culture test) were validated against a set of test chemicals characterized by high levels of in vivo embryotoxicity data in laboratory animals and humans. In a validation study in Europe, the EST was found to be reproducible, demonstrating an overall accuracy of 80% and 100% correct prediction of strong embryotoxicity for chemicals studied under blind conditions. However, use of EST is impossible for the nanomaterial which is not dissolved in a culture medium. Therefore, some improvement of EST protocol is proposed.