A bracket device includes a bracket, a mounting member and a locking member. The bracket includes a first end part and a second end part. A space is defined between the first end part and the second end part. The mounting member is arranged adjacent to the first end part of the bracket. The mounting member has a mounting part located in the space. The locking member is arranged on the bracket and includes a locking part and an operating part. Wherein, the locking part of the locking member is held to be located at a position in the space of the bracket. The locking part of the locking member is able to be moved away from the position in response to operation of the operating part of the locking member. Wherein, the operating part of the locking member is not located in the space of the bracket.