This study focuses on the fact that tactile factors, compared to visual factors, have not been effectively applied to enhance the usability of control panels. It also evaluates the effectiveness of allocating a rough/smooth feeling to the surface of each button in a control panel according to its operational function. The first experiment reveals relationships between some of the impressions concerning the operation of electrical appliances and the rough/smooth feeling when touching the surface of buttons. Moreover, it provides specific information on what degree of roughness/smoothness should be applied to what types of functional buttons. The second experiment demonstrates that the usability of control panels can be enhanced by providing a rough/smooth feeling to each button, considering suitability with respect to operation impressions. In addition, results indicate that users may feel discomfort when the rough/smooth feeling does not correspond to operation impressions.