Abstract: The present invention provides a thin magnetic tape for allowing a long play without degrading electro-magnetic transfer characteristics and mechanical strength of the magnetic tape. The magnetic tape comprises a base film, an an under layer provided on the base film, and a magnetic layer containing magnetic particles coated on the under layer. The under layer contains magnetic plate-particles each having a configuration such that a ratio of a major axis to a minor axis observed in a plate-like surface is preferred to be approximately 1 and a ratio of the major axis to a thickness off the magnetic particles is to be 5.about.10 so that the under layer has Young's modulus of not less than 2.0.times.10.sup.10 N/m.sup.2 in a longitudinal direction of the magnetic tape and has virtually the same value in a traversing direction thereof.