We have used anodic oxidation of titanium for the first time to develop an oscillating weight in order to improve the decorative effect of mechanical watch. It was found that the coloring behavior of titanium anodization was strongly influenced by the surface condition caused by machining. The presence of the affected layer on the surface prevents the uniformity of color. We derived the etching conditions for removing the affected layer. As a result, it was possible to realize the designed color with high repeatability.