A modular audio-visual device comprises of a first or a second supporting element connected to a traffic means for supporting other elements, an audio-visual device sustaining element, a display device sustaining element, and a plurality of sets of fixing elements for fixing supporting element and sustaining element. The characteristic of the present invention is that the component elements can be assembled into a module for diversified use or kept alone for simple use. The device according to the present invention can be used in various traffic means. The user can freely choose and buy component elements to assemble into a device with only display function, or with only audio-visual function, or with both display and audio-visual functions. The present invention has the advantages of diversified selection and convenience for user.