Abstract: An object of the invention is to realize a frame converter which successively can output an image signal in synchronous situation with a switching of asynchronous image signals by using a frame memory of which a number is smaller than of the inputted image signal. A frame converter according to the invention characterized by comprising, signal inputting means 11 and 12 for receiving image signals, identification signal assigning means 14 and 24 for assigning an identification signal to non-image area of the image signal from the signal inputting means for identifying the image signal, storing means 16 and 25 for storing the image signal form the signal inputting means for each frame, and signal outputting means 31 for outputting the image signal which is stored in the storing means by reading alternatively.