A foamed liquid coating apparatus prevents curling or warping of a sheet caused by coating irregularities when coated with a preprocessing solution using a coating roller or a liquid discharge head. The foamed liquid coating apparatus includes a container holding a liquid that can be foamed. A first foamed liquid producing/transporting unit produces a foamed liquid having a foam size greater than a required foam size from the liquid supplied from the container. A second foamed liquid producing/transporting unit produces a foamed liquid having the required foam size from the foamed liquid produced by the first foamed liquid producing/transporting unit. The foamed liquid produced by the second foamed liquid producing/transporting unit is applied onto a first coating roller. The foamed liquid is further supplied from the first coating roller to a second coating roller that coats a sheet with the foamed liquid.