Head-attached interface device (HIDE) has been developed as a new type of wearable computer in an actual work environment. HIDE has flexible integrated functions which consist of speech recognition and view direction detection as hands-free operation methods, see-through display and audio guidance as information presentation methods. In this paper, the design concept of HIDE is first described, and the individual functions to configure the design concept and overall configuration are explained. Then, an integrated prototype system of HIDE has been produced, and its functional evaluation tests were conducted to examine the individual functions with re-spect to resolution of displayed image, speech recognition rate, and detection rate/time of view direction. Finaly, a WWW browser was made as an example application software for testing and repairing electric circuit board, in order to confirm the integrated functions of HIDE.