Tactile feedback of the quantified shape feature according the tactual exploration with an interface is required. Electrotactile display fits together with an input interface because of its small and simple stimulator. The level of the self-similarity is one of the quantified shape features of an object. In order to present a self-similar object, the electrotactile display which can control the sensation of the skin indentation is required. In this study, we proposed the representation of the skin indentation by modulating with pulse rate of the uni-stimulus to present self-similarity of an object. To calculate the stimulus according to the tactual tracing of an arbitrary surface, the simplified skin indentation is estimated and modulated by the pulse rate. Furthermore, the developed electrotactile mouse had an anode and a ground electrodes to present the stimulus at a fingertip during the manipulation. The relationship between pulse rate and the sensory intensity of the skin indentation and the discrimination of the dimension of the self-similarity were examined. The results indicated that electrotactile pulse rate modulation of the skin indentation was effective below the pulse rate 100pps, and users could discriminate the level of the self-similarity.