A transfer device comprising: an image carrier ; a nip forming member that abuts against a surface of the image carrier carrying a toner image so as to form a transfer nip; and a transfer voltage application unit including a secondary transfer power supply , that applies a transfer voltage to the transfer nip, the transfer voltage including a DC component and an AC component for transferring the toner image on the image carrier onto a recording material (P) nipped in the transfer nip, wherein when the toner image on the image carrier is transferred onto the recording material (P), the transfer voltage is an alternating voltage in which a supply voltage having polarity in a transfer direction in which the toner image is transferred onto the recording material (P) from the image carrier and a return voltage having polarity opposite to the supply voltage are switched alternately, a time average value Vave of the transfer voltage is set to be at polarity in the transfer direction in which the toner image is transferred onto the recording material (P) from the image carrier and is set to be closer to a peak value Vt of the supply voltage relative to a center value Voff between a maximum value and a minimum value of the transfer voltage, and an absolute value of the peak value Vr of the return voltage is set to be larger than an absolute value of the time average value Vave; characterized in that : the secondary transfer power supply is configured to output a voltage having a waveform of a rectangular shape with corners that are chamfered, wherein a rectangular wave indicates a wave having a waveform in which a period at a peak value is equal to or higher than 60 % of the total in each of the application periods of the return voltage and the supply voltage. an image carrier ; a nip forming member that abuts against a surface of the image carrier carrying a toner image so as to form a transfer nip; and a transfer voltage application unit including a secondary transfer power supply , that applies a transfer voltage to the transfer nip, the transfer voltage including a DC component and an AC component for transferring the toner image on the image carrier onto a recording material (P) nipped in the transfer nip, wherein when the toner image on the image carrier is transferred onto the recording material (P), the transfer voltage is an alternating voltage in which a supply voltage having polarity in a transfer direction in which the toner image is transferred onto the recording material (P) from the image carrier and a return voltage having polarity opposite to the supply voltage are switched alternately, a time average value Vave of the transfer voltage is set to be at polarity in the transfer direction in which the toner image is transferred onto the recording material (P) from the image carrier and is set to be closer to a peak value Vt of the supply voltage relative to a center value Voff between a maximum value and a minimum value of the transfer voltage, and an absolute value of the peak value Vr of the return voltage is set to be larger than an absolute value of the time average value Vave; characterized in that : the secondary transfer power supply is configured to output a voltage having a waveform of a rectangular shape with corners that are chamfered, wherein a rectangular wave indicates a wave having a waveform in which a period at a peak value is equal to or higher than 60 % of the total in each of the application periods of the return voltage and the supply voltage. <EOS>