PURPOSE: To raise S/N, and to prevent cinching phenomenon, dropout of a back coat layer, damage of a tape during traveling, and deviation and irregular winding of the tape during high-speed winding, by dispersing into a binder, particles selected from inorganic pigments having 0.1W0.5μm average particle size, and 2W4, and 5W7 Mohs' hardness as a filler of the back coat layer.

CONSTITUTION: CaCO3, etc. are suitable for an inorganic pigment having 0.1W 0.5μm average particle size and 2W4 Mohs' hardness, and TiO2, γ-Fe2O3, etc. are suitable for an inorganic pigment having 5W7 Mohs' hardness. These inorganic pigment particles different from each other in Mohs' hardness are mixed in 9:1W5:5 weight ratio, the mixture is dispersed into a binder and kneaded in 4;1W1:1 weight ratio, and a back coat layer is formed by using the obtained coating material so as to give 0.3W1.5 coat film thickness and 0.1W0.5 surface roughness. As a result, the obtained back coat layer enhnaces S/N, and prevents cinching phenomenon.