A transfer device includes a controller that controls a transfer bias supply to cause a transfer bias to increase, between an image carrier and a first rotary body disposed opposite the image carrier, a potential of the first rotary body toward an opposite polarity to a charge polarity of toner of a toner image on the image carrier to be higher than a potential of the image carrier, and to change, on the basis of identified recording medium type, a returning peak value which is one of a peak value of positive polarity and a peak value of negative polarity of the transfer bias and which generates an electric field that causes the toner having moved to the recording medium from the image carrier to return to the image carrier from the recording medium in a transfer nip.