A device for spraying a coating chemical onto a moving surface ( 1 ) of a papermaking machine includes a machine-wide box body ( 2 ) extending in a cross machine direction and defines an internal space configured to enclose part of a spraying equipment ( 3 ) and also defines an elongate opening ( 22 ) facing said moving surface ( 1 ). The spraying equipment ( 3 ) includes a plurality of spray nozzle members ( 30 ) for spraying coating chemical through said opening ( 22 ) onto the moving surface ( 1 ), a coating chemical supplying tube ( 32 ) is connected to the nozzle members ( 30 ), and a plurality of valves ( 33 ) are mounted on the coating chemical supplying tube ( 32 ), one for each nozzle member ( 30 ). To make it possible to change a nozzle member ( 30 ) without requiring that the coating chemical supplying tube ( 32 ) has to be pulled out of the box body ( 2 ), and where the nozzle change can be carried out with less risk for the operator to any danger, the coating chemical supplying tube ( 32 ) with said valves ( 33 ) is located outside of the box body ( 2 ), and the nozzle members ( 30 ) extend through a wall portion ( 36 ) of the box body ( 2 ) and are mounted to be individually movable axially to permit removal of anyone of them independently of the other ones.