PURPOSE: To realize the video signal synthesizing device which obtains smooth edges and intersection areas.

CONSTITUTION: This device is provided with a circuit 10 which generates priority signals, circuits 211 to 213 which generate complementary signals of key signals, circuits 214 to 216 which generate complementary signals of priority signals, a circuit 30 which multiplies all complementary key signals and outputs the resultant complementary signal as a synthesized key signal, a circuit 40 calculates a reciprocal of the synthesized key signal to generate a synthesized key reciprocal signal, circuits 51 to 53 which add complementary priority signals and complementary key signals of picture signals as weighting objects to video signals of picture signals, key signals, and priority signals for these picture signals and multiplies resultant signals to perform the shaping processing of respective video signals, a circuit 60 which adds video signals subjected to the shaping processing, and a circuit 70 which multiplies the video signal obtained by this addition and the synthesized key reciprocal signal to generate a synthesized picture signal, thus simultaneously synthesizing three or more picture signals.