PURPOSE: To increase the speed of coating and improve the productivity at the time of uniformly applying a coating on a base paper with a blade by detecting the vibration displacement of the blade with a vibration sensor to predict the bleeding.

CONSTITUTION: A coating is uniformly applied on a base paper with the blade of a coating machine. In this case, a vibration sensor 3 is fixed to the blade 1 through a supporting part 2. Bleeding is predicted based on the vibration displacement of the blade 1 detected by the sensor 3. Namely, the vibration displacement of the blade 1 is constantly monitored, and a countermeasure is taken to avoid the bleeding before the displacement reaches a limit value. Consequently, coating is performed at a high speed while avoiding occurrence of bleeding, and productivity is improved.