A mouth mirror apparatus includes a carrier seat that has first and second receiving spaces and multiple outlet passages embedded in a surrounding wall and intercommunicating the first and second receiving spaces. The mouth mirror apparatus further includes a handle grip cooperating with the carrier seat to define an air inlet passage that communicates with the second receiving space, a mirror body rotatably disposed in the first receiving space, and an impeller connected to the mirror body and driven by air which flows from the air inlet passage. Through combination of the mirror body, the impeller, and the arrangement of the air outlet passages, the mouth mirror apparatus can direct air current to render different functions.