An image decoding device and method analyzes a parameter of the encoded bit stream to restore a 1-bit information to indicate that temporal distance between any two successive video frames to be displayed is constant in the video sequence, the 1-bit information being analyzed prior to a decoding process for a data area representing the video frames, A VOP decoder decodes a VOP that is image data serving as an encoding unit of video object and a VOL header analyzing part decodes a VOP rate flag, contained in encoded form in a header information part of a VOL layer composed of several VOPs, for indicating that a display rate in the VOL of the VOP to be decoded by the VOP decoder is a fixed rate by the VOP rate flag only.