The magnetic tape includes: a non-magnetic support; and a magnetic layer including ferromagnetic powder, in which the ferromagnetic powder is ferromagnetic powder selected from the group consisting of hexagonal strontium ferrite powder and ε-iron oxide powder, and an amount of an edge weave of a tape edge on at least one side of the magnetic tape is 1.5 μm or less.

A magnetic recording medium is provided and includes a layer structure including a magnetic layer, a non-magnetic layer, and a base layer in order, in which an average thickness t.sub.T of the magnetic recording medium is 4.0 μm≤t.sub.T≤5.3 μm, a dimensional variation Δw in a width direction of the magnetic recording medium to tension change in a longitudinal direction of the magnetic recording medium is 680 ppm/N≤Δw≤2000 ppm/N , and an average thickness t.sub.n of the non-magnetic layer is t.sub.n≤1.0 μm.

The average thickness t.sub.T of a magnetic recording medium meets the requirement that t.sub.T≤5.5 [μm], and the dimensional change amount Δw in the width direction of the magnetic recording medium with respect to the tension change in the longitudinal direction of the magnetic recording medium meets the requirement that 700 ppm/N≤Δw.

A magnetic recording medium is provided and includes a substrate; and a magnetic layer provided over the substrate, wherein (wmax−wmin)/wmin≤400 [ppm] . . . (1) where wmax and wmin are respectively maximum and minimum of average values of width corresponding to samples of magnetic recording medium measured after the samples are stored for two hours under storage conditions (a loading tension in the longitudinal direction of the magnetic recording medium, a temperature and a relative humidity) for each of the samples, and a width of a sample of the magnetic recording medium at 25° C. and 50% relative humidity and without loading is ½ inch, magnetic recording medium has Young's modulus of less than 8.0 GPa in a longitudinal direction, and 4.0≤TB/(TA−TB) . . . (2) where TA is average thickness of magnetic recording medium and TB is average thickness of substrate.

In a magnetic recording medium, an average thickness t.sub.T is t.sub.T≤5.5 μm, a dimensional variation Δw in a width direction to tension change in a longitudinal direction is 650 ppm/N≤Δw, and a rate of shrinkage in the longitudinal direction is 0.08% or less.

A magnetic tape device, a magnetic tape, and a magnetic tape cartridge, in which the magnetic tape is caused to run between a winding reel and a cartridge reel in a state where a tension is applied in a longitudinal direction of the magnetic tape and a maximum value of the tension is 0.50 N or more, the magnetic tape after running in a state where the tension is applied is wound around the cartridge reel by applying a tension of 0.40 N or less in the longitudinal direction, and a center line average roughness Ra measured regarding a surface of a back coating layer of the magnetic tape with an atomic force microscope is in a range of 5 to 13 nm.

The magnetic tape includes a non-magnetic support, a magnetic layer that includes ferromagnetic powder having an average particle volume of 2,500 nm.sup.3 or less on one surface side of the non-magnetic support, and a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support, in which the ferromagnetic powder is ferromagnetic powder selected from the group consisting of hexagonal ferrite powder and ε-iron oxide powder, and a ratio (PSD.sub.5 μm-PSDmag/PSD.sub.10 μm-PSDbc) of the magnetic layer and the back coating layer is in a range of 0.0050 to 0.20. A magnetic tape cartridge and a magnetic recording and reproducing apparatus include the magnetic tape.

Provided are a magnetic tape comprising a magnetic layer containing a ferromagnetic powder and a binding agent on a non-magnetic support, in which the magnetic layer contains an oxide abrasive, an average particle diameter of the oxide abrasive obtained from a secondary ion image acquired by irradiating a surface of the magnetic layer with a focused ion beam is 0.04 μm to 0.08 μm, and an absolute value ΔN of a difference between a refractive index Nxy measured with respect to an in-plane direction of the magnetic layer and a refractive index Nz measured with respect to a thickness direction of the magnetic layer is 0.25 to 0.40, and a magnetic recording and reproducing device including the magnetic tape.

A magnetic recording medium is provided and includes a magnetic layer, a non-magnetic layer, a base layer and a back layer, wherein an average thickness t.sub.T of the magnetic recording medium is t.sub.T≤5.3 a dimensional change amount Δw in a width direction with respect to a change in tension in a longitudinal direction is 700 ppm/N≤Δw, a thickness of the non-magnetic layer is 2.0 μm or less, a squareness ratio measured in a vertical direction of the magnetic recording medium is 65% or more, and the magnetic layer includes a magnetic powder.

In the magnetic recording medium, a number distribution A of a plurality of bright regions, based on equivalent circle diameters thereof, in a binarized image of a secondary electron image obtained by imaging a surface of the magnetic layer by a scanning electron microscope at an acceleration voltage of 5 kV and a number distribution B of a plurality of dark regions, based on equivalent circle diameters thereof, in a binarized image of a secondary electron image obtained by imaging a surface of the magnetic layer by a scanning electron microscope at an acceleration voltage of 2 kV respectively satisfy a predetermined number distribution.