To provide a varnish coater which utilizes a stencil process printer of conventional common digital plate making-type and enables simple/convenient applying of a uniform varnish film to a specified area of the surface or cover of printed matter by any user.

This varnish coater 39 functions as such in case a varnish coating unit 20 is installed and set at a mounting part of a printer body 100 in lieu of a drum unit 40. The varnish coating unit 20 comprises (1) a feeder device including a coating roller 8 which applies a transparent varnish solution to the surface of a printed sheet 2 and feeds this sheet 2 and a doctor roller 21 which has a solution reservoir 22 formed right above the coating roller 8 and supplies the varnish solution in a specified thickness across the specified extent of the coating roller 8 surface, (2) a retainer base 24A for detachably retaining a varnish container 24 and (3) a pumping device 26 etc.