A case structure of an electronic device includes a main case, a cover, and an elastic driving element. The main case includes a hollow portion, and a spring leaf structure protruding inwardly from a side of the hollow portion. The cover for covering the hollow portion includes a fastening portion, at least one fixing element, and a column portion. The elastic driving element is movably combined with the main case and includes a corresponding fastening portion and an operating portion. When the cover is combined with the main case, the spring leaf structure is pressed by the column portion to generate an elastic deformation; when the operating portion is moved to let the corresponding fastening portion detach from the fastening portion, the cover may detach from the main case with an elastic restoring force exerted by the spring leaf structure on the column portion.