The present disclosure discloses a transformed Synechococcus elongatus strain capable of producing biodiesel directly from carbon dioxide and a method for producing biodiesel and a method for removing carbon dioxide using the same. In an aspect, the transformed Synechococcus elongatus strain of the present disclosure can produce biodiesel in large scale using carbon dioxide as a carbon source. The Synechococcus elongatus strain is environment-friendly because it can be used to remove or reduce carbon dioxide in the atmosphere. The strain of the present disclosure is advantageous in that it can produce biodiesel in large scale because it grows faster and exhibits excellent carbon dioxide fixation capability as compared to other photosynthetic microorganisms.