A transfer device includes a conveyance belt, a transfer roller, and a stretch roller. The conveyance belt is in contact with an image carrier that carries a toner image, and conveys a sheet via a contact position with the image carrier. A voltage having a polarity opposite to a charging polarity of toner that forms the toner image is applied to the transfer roller, and the transfer roller transfers the toner image carried by the image carrier onto the sheet at the contact position. The stretch roller stretches the conveyance belt at a separation position in which the sheet is separated from the conveyance belt and which is downstream of the contact position in a conveyance direction in which the sheet is conveyed by the conveyance belt, and the voltage having the polarity opposite to the charging polarity of the toner is applied to the stretch roller.