To provide a tin plating method and tin plating device, which can highly efficiently remove sludge attached on a surface of tin ion supply source.

There is provided the tin plating method which applies tin plating to plating objects immersed in a plating liquid held in a plating liquid tank. The method includes steps of: removing the sludge attached on the surface of tin bars 21; and applying tin plating to the plating objects by energizing the tin bars 21 from which the sludge is removed as an anode and the plating objects as a cathode. In the step of removing the sludge, at least either of the tin bars 21 or sludge removing bars 22 arranged in contact with the tin bars 21 rotates so that the sludge attached on the surface of the tin bars 21 is removed.