Embryonic stem (ES) cells can self-renew maintaining the undifferentiated state. Self renewal requires many factors such as Oct4, Sox2, FoxD3, and Nanog. NF-${kappa}B$ is a transcription factor involved in many biological activities. Expression and activity of NF-${kappa}B$ increase upon differentiation of ES cells. Reportedly, Nanog protein directly binds to NF-${kappa}B$ protein and inhibits its activity in ES cells. Here, we found a potential binding site of NF-${kappa}B$ in the human Nanog promoter and postulated that NF-${kappa}B$ protein may regulate expression of the Nanog gene. We used human embryonic carcinoma (EC) cells as a model system of ES cells and confirmed decrease of Nanog and increase of NF-${kappa}B$ upon differentiation induced by retinoic acid. Although deletion analysis on the DNA fragment including NF-${kappa}B$ binding site suggested involvement of NF-${kappa}B$ in the negative regulation of the promoter, site-directed mutation of NF-${kappa}B$ binding site had no effect on the Nanog promoter activity. Furthermore, no direct association of NF-${kappa}B$ with the Nanog promoter was detected during differentiation. Therefore, we conclude that NF-${kappa}B$ protein may not be involved in transcriptional regulation of Nanog gene expression in EC cells and possibly in ES cells.