PURPOSE: To provide a means wherein stain and decrease in quality caused by excess coating on a paper-joined part when a frame is exchanged can be avoided and deformation and wear based on frictional heat of a coating blade can also be avoided.

CONSTITUTION: In a blade coater wherein a coating 5 is applied on the surface of a continuously running base paper 2 through a backing roll 1 from a slit-like extrusion hole 4 for the coating of a coater head 3 and then, an amt. of coating is set by means of a coating blade 6, only for a definite period where the base paper 2 of the former base paper roll is joined together with the start end part of a new base paper roll under running condition during coating and this paper-joined part passes through the coating position, applying of the coating 5 from the extrusion hole 4 is stopped and water is sprayed on the surface of the base paper 2 from a water ejecting hole 9 of the coater head 3.