PURPOSE: To realize a work station applied to broad range including not only a document and a graphic but also an animation by synthesizing information by means of a computer and information by means of a video signal, and displaying it.

CONSTITUTION: The display information outputted from the computer is held in a window picture memory 1, the video signal from a VTR, etc., is converted by a video signal converting mechanism 2, held in a video information picture memory 3, and the computer notifies which VTR signal is displayed on which window to a display area control mechanism 4. Based on the decision result of the display area control mechanism 4, a window picture switching mechanism 5 selects either one of the picture memory, outputs it to a display device, and on the display device, the display information from the computer and the video information from the VTR, etc., are synthesized and displayed. Thus, the work station for multiple purposes including not only the document and graphic but also animation information can be realized.