An image forming apparatus includes: a treatment liquid application device which applies a treatment liquid to a recording medium; a treatment liquid supplying device which abuts against the treatment liquid application device so as to form a liquid holding space, fills the treatment liquid into the liquid holding space by use of a liquid delivery device which delivers the treatment liquid to the liquid holding space via a first flow channel from a treatment liquid reservoir storing the treatment liquid, and restores the treatment liquid to the treatment liquid reservoir via a second flow channel from the liquid holding space; a controller which controls at least one of a treatment liquid filling operation and a treatment liquid restoring operation with respect to the liquid holding space; an ink ejecting device which ejects a droplet of an ink onto the recording medium to which the treatment liquid application device has applied the treatment liquid; and an air bubble mixing avoidance device which is provided in the second flow channel and prevents air from discharging in the treatment liquid in the treatment liquid reservoir.