A curtain coating device for paper and board machines has a nozzle beam (10) with a nozzle lip (12) with an edge strip (11) for feeding the coating color curtain and edge guides (20) located along each edge of the nozzle lips (12) controlling the width of the coating color curtain. The edge guide (20) has upper and lower ends. Flow surfaces (22) extend in a substantially vertical direction parallel and next to each other. The edge guide has a lubrication feed (24), additional lubrication feeds (26) and a suction opening (27). The flow surfaces (22) are inclined toward each other forming a flow guide recess (25) which extends in a vertical direction such that the form of the flow surfaces (22) with the flow guide recess (25) is concave. A protrusion (21) extends within the recess in the direction of the flow guide recess (25).