A capacitive touchpad integrated with key and handwriting functions is provided for operation in key, handwriting and mouse modes. Several regions are defined on the panel of the touchpad and have several patterns printed thereon for the operation modes thereby. In the key mode, the key patterns among the printed patterns simulate a keyboard. In the handwriting mode, the handwriting region among the defined regions serves to handwriting input. In the mouse mode, the defined regions provide a cursor moving region and a horizontal and vertical scroll bars for input operations.