The present invention relates to an image processing device and method enabling deterioration in encoding efficiency to be suppressed.A control information adding unit 184 embeds one picture worth of control information held in a control information holding unit 183 into a slice header of a predetermined slice, in encoded data held in an encoded data holding unit 182. For example, the control information adding unit 184 embeds one picture worth of control information in the slice header of the first-transmitted slice in the frame to be processed in the encoded data. The control information adding unit 184 outputs encoded data to which the control information has been added, in a predetermined order. The present invention can be applied to, for example, an image processing device.