An image-forming apparatus includes an image-carrying belt that is rotated while carrying toner images on an outer circumferential surface thereof; a movable tensioner applying tension to the image-carrying belt, a position of the tensioner being changed while being in contact with the inner circumferential surface of the image-carrying belt, the tensioner being electrically grounded or a voltage being applied to the tensioner; and an electrode member, a position of the electrode member being changed in conjunction with a change of the position of the tensioner so as to maintain a predetermined distance from the image-carrying belt, the electrode member being electrically grounded or a voltage being applied to the electrode member.