At least one kind of control signal concerning control of contents, added to specific locations inside contents data, is detected as first control information, and at the same time, at least one kind of control information concerning control of contents, embedded inside the contents data by a digital watermark, is detected as second control information. Consistency between the first control information as detected, and the second control information as detected is determined and on the basis of results of the determination, the control of the contents is executed. Thus, it is possible to reduce a possibility of the contents being improperly copied, thereby enabling the control with assurance of still higher safety.