A mouth mirror apparatus is adapted to be connected to a suction device and includes a mounting frame (1), an elongated handle (12), and a mirror member (2). The mirror member (2) is rotatably mounted on a major wall (11) of the mounting frame (1) and can be driven to rotate when the suction device is actuated. When the mirror member (2) rotates, a centrifugal force is generated to fling off water drops and/or debris on a reflecting surface (211) of the mirror member (2).