A method for controlling a masking block in a monitoring camera. The method adjusts the masking block to precisely hide an image of a subject with its position and size changed when a zoom magnification is changed under a state where the masking block is set. In addition, the method adjusts a masking block to precisely hide a changed image of a subject when the monitoring camera is rotated to change the position of the image of the subject. In addition, the method measures and corrects a distance between a center axis of a CCD and an optical axis of a lens if the two axes are not coincident with each other. In addition, the method corrects an offset occurring due to an incorrect coupling between the monitor camera and a pan/tilter. Furthermore, a method for setting a masking block when a remotely uncontrollable monitoring camera is used is disclosed.