To provide a video signal processor which can correct the OB(optical black) difference due to an image pickup element of an image pickup device with one adjustment with respect to circuit while accurately following the temperature change.

A means 91 which calculates the OB level of a video signal obtained from the image pickup element, a coefficient calculation means 92, and a subtraction circuit 93 are provided, and the output of the OB level calculation means 91 is multiplied by a coefficient in the coefficient calculation means 92 to generate an OB difference signal accurately following even the temperature change, and the subtraction means 93 is used to subtract the OB difference signal from a video signal 95 obtained from the image pickup element, thereby preventing the occurrence of correction error.