In an information transmission method, error robustness is provided for the bit stream itself so that decoding processing can be properly performed even in the event of an error in important information such as header information. A bit stream reconstruction circuit (107) in an encoding apparatus adds sync signals to the heads of encoded data streams, which are encoded by an encoder (103), in certain bit stream units, and then inserts designation information in each bit stream by using a designation information insertion circuit (106). Each designation information indicates the addition of information for reconstructing important header information. By inserting the designation information in the bit stream obtained, reconstruction information can be added to the bit stream. Even if, therefore, an error is introduced into the header information, and the information cannot be used for decoding processing, the decoding processing can be properly continued by using the new reconstruction information designated by the designation information as a substitute.