An image forming system includes an image forming apparatus that forms an image on a sheet, and a finisher that performs a post-printing process with the sheet. The image forming system comprises: a paper path through which the sheet is passed; an electricity eliminator that is arranged in the upstream side of the finisher to apply at least one agent of water and charge to the sheet; and a hardware processor that controls an application amount of the agent to be applied to the sheet by the electricity eliminator based on an amount of charge which is generated on the sheet when the sheet is passing through the paper path.