An operation input control device comprising: a screen display control section configured to perform control such that at least one screen is displayed on a display surface of a display section in a manner that allows the at least one screen to change in position or in size; a region position control section configured to generate an operation control region in a form of a window in such a manner that the operation control region is superimposed on the screen and is associated with the screen, the operation control region being a region for making valid or invalid a position input operation performed on the screen, and characterized to control a position of the operation control region such that the operation control region changes with a change to the associated screen, by calculating coordinates of the operation control region after movement which is associated with the changed screen by adding a movement distance of the screen to coordinates of the operation control region before the movement; or calculating coordinates of the operation control region after a size change which is associated with the changed screen by multiplying a length of a diagonal line of the operation control region before the size change by a ratio between a length of a diagonal line of the screen before the size change and a length of a diagonal line of the screen after the size change; or calculating coordinates of the operation control region after the size change which is associated with the changed screen by multiplying a difference between respective coordinates at diagonal vertices of the operation control region before the size change by a ratio between a difference between respective coordinates at diagonal vertices of the screen before the size change and a difference between respective coordinates at diagonal vertices of the screen after the size change. a screen display control section configured to perform control such that at least one screen is displayed on a display surface of a display section in a manner that allows the at least one screen to change in position or in size; a region position control section configured to generate an operation control region in a form of a window in such a manner that the operation control region is superimposed on the screen and is associated with the screen, the operation control region being a region for making valid or invalid a position input operation performed on the screen, and characterized to control a position of the operation control region such that the operation control region changes with a change to the associated screen, by calculating coordinates of the operation control region after movement which is associated with the changed screen by adding a movement distance of the screen to coordinates of the operation control region before the movement; or calculating coordinates of the operation control region after a size change which is associated with the changed screen by multiplying a length of a diagonal line of the operation control region before the size change by a ratio between a length of a diagonal line of the screen before the size change and a length of a diagonal line of the screen after the size change; or calculating coordinates of the operation control region after the size change which is associated with the changed screen by multiplying a difference between respective coordinates at diagonal vertices of the operation control region before the size change by a ratio between a difference between respective coordinates at diagonal vertices of the screen before the size change and a difference between respective coordinates at diagonal vertices of the screen after the size change.