An image forming apparatus comprising: a photosensitive member; a charging means supplied with a charging bias and configured to charge said photosensitive member; an exposure means configured to expose said photosensitive member and to form an electrostatic latent image; a developing means configured to carry a liquid developer containing toner and a carrier liquid, and to develop the electrostatic latent image formed on a surface of said photosensitive member into a toner image by being contacted with the surface of said photosensitive member at a developing portion and by being supplied with a developing bias; a transfer means configured to transfer the toner image from said photosensitive member at a transfer portion by being supplied with a transfer bias; a transfer voltage source capable of applying the transfer bias to the transfer means; a detecting portion configured to detect at least one of a voltage supplied to the transfer means and a current flowing through the transfer means; and a controller configured to set the transfer bias on the basis of a detection result of said detecting portion when a setting bias is applied from said transfer means, wherein, before execution of an image forming job after main switch actuation or in a pre-rotation during the image forming job, said controller causes said charging means to charge the surface of said photosensitive member to a dark-portion potential, executes an operation in which the carrier liquid is deposited on the surface of said photosensitive member not to supply the toner from said developing means when the surface of said photosensitive member charged to the dark-portion potential passes through said developing portion, and causes said transfer voltage source to apply the setting bias when an area of said photosensitive member passing through said developing portion during the operation is positioned at said transfer portion. a photosensitive member; a charging means supplied with a charging bias and configured to charge said photosensitive member; an exposure means configured to expose said photosensitive member and to form an electrostatic latent image; a developing means configured to carry a liquid developer containing toner and a carrier liquid, and to develop the electrostatic latent image formed on a surface of said photosensitive member into a toner image by being contacted with the surface of said photosensitive member at a developing portion and by being supplied with a developing bias; a transfer means configured to transfer the toner image from said photosensitive member at a transfer portion by being supplied with a transfer bias; a transfer voltage source capable of applying the transfer bias to the transfer means; a detecting portion configured to detect at least one of a voltage supplied to the transfer means and a current flowing through the transfer means; and a controller configured to set the transfer bias on the basis of a detection result of said detecting portion when a setting bias is applied from said transfer means, wherein, before execution of an image forming job after main switch actuation or in a pre-rotation during the image forming job, said controller causes said charging means to charge the surface of said photosensitive member to a dark-portion potential, executes an operation in which the carrier liquid is deposited on the surface of said photosensitive member not to supply the toner from said developing means when the surface of said photosensitive member charged to the dark-portion potential passes through said developing portion, and causes said transfer voltage source to apply the setting bias when an area of said photosensitive member passing through said developing portion during the operation is positioned at said transfer portion.