An image scanning apparatus includes a base, a transparent plate, a guide rod disposed between the base and the transparent plate, an optical sensor module, and a carrier mounted on the guide rod and including a first support bracket to place the optical sensor module thereto and having a first pivot connecting portion, a second support bracket having a second pivot connecting portion connected pivotally to the first pivot connecting portion, and an elastic member disposed between the first and second support brackets and biasing upwardly the first support bracket so as to keep the optical sensor module in constant contact with the transparent plate.