In this paper, we present a watermarking scheme based on the DWT (Discrete Wavelet Transform) and the ART2 to ensure the copyright protection of the digital images. The problem to embed watermark is not clear to select important coefficient. We used the ART2 to solve it. We didn’t apply the whole wavelet coefficients, but applied to only the wavelet coefficients in the selected cluster. Disadvantage of ART2 is different train data according to sequence of input data, but it becomes advantage of watermarking. Using the ART2 that even the watermark casting process and watermark verification process are in public, nobody knows about the location of embedding watermark except of authorized user. As the result, the watermark is good at the strength test-filtering, geometric transform and etc.