An after-dryer and method for drying a surface-treated paper web in an after-dryer of a paper machine in which the web is first finished in a finishing section, i.e., surface-sized or coated, by a finishing device and then dried. In the after-dryer, the paper web is dried in at least one dryer group that makes use of single-wire draw and at the same time, the paper web is dried by an impingement-drying equipment arranged in connection with at least one cylinder or roll in the single-wire dryer group.