Patent ID: 7381481

Claim:
A magnetic tape comprising: a longitudinally extending nonmagnetic support having a longitudinal direction and a width direction; a magnetic layer formed by depositing a plurality of evaporated metal magnetic films on the longitudinally extending nonmagnetic support, each having an oblique column-like structure, on a principal surface of said nonmagnetic support so that a growth direction of each of said deposited evaporated metal magnetic films is opposite to said growth direction of the previously deposited evaporated metal magnetic film, said magnetic layer having a double-layered structure composed of a lower metal magnetic thin film and an upper metal magnetic thin film; a protective layer formed on said magnetic layer; and a backcoating layer formed on the other surface of said longitudinally extending nonmagnetic support, wherein, a heat-shrinkage ratio in said longitudinal direction and a width direction is 0.50% or less, a humidity expansion coefficient is 1×10 −6 /% RH or less after stock at 100° C. and 5% RH for 30 minutes, a total thickness of said longitudinally extending nonmagnetic support is from 4.0 μm to 10.0 μm so that said heat-shrinkage ratio and said humidity expansion coefficient satisfy said conditions, a total thickness of said magnetic layer is from 10 nm to less than 50 nm so that said heat-shrinkage ratio and said humidity expansion coefficient satisfy said conditions, and a ratio of a total thickness of said magnetic tape to the total thickness of said magnetic layer of 1000 or less so that said heat-shrinkage ratio and said humidity expansion coefficient satisfy said conditions.