Control device for a computer mouse. In order to enhance comfort as much as possible and to avoid or even cure RSI phenomena, a control device is proposed with a curved finger-supporting element and thumb-supporting element with varying curvatures. Optimum support for the hand and fingers (thumb) is obtained if there is a certain correlation between the length over which the hand, including the fingers, is supported and the width available for supporting the fingers. This value is preferably in the range 0.3-0.6 and more specifically is 0.45. Furthermore, the curvature and height of the finger-supporting element and thumb-supporting element must be implemented such that they are a function of the length of the control device. According to a particular embodiment the finger-supporting element is implemented such that, when viewed transversely, this descends from the highest point in a circle.