A fan device includes a bottom shell, a cover, and an impeller. The cover includes a main body, a support, and a spoiler. The main body has a through opening. A connection position between the support and the main body has a first folding line. The support is bended along the first folding line to form a portion of the through opening. The support is perpendicular to the main body, and is abutted against the bottom shell. A connection position between the spoiler and the main body has a second folding line. The spoiler is bended along the second folding line to locate in the through opening. An acute angle is formed between the spoiler and the surface of the main body facing away from the bottom shell. The impeller is located in an accommodating space between the cover and the bottom shell.