The magnetic tape includes a non-magnetic support, and a magnetic layer including a ferromagnetic powder. The non-magnetic support is a polyamide support, and a deformation rate ratio of a deformation rate in a width direction to a deformation rate in a longitudinal direction of the magnetic tape, (the deformation rate in the width direction/the deformation rate in the longitudinal direction), is 0.45 or less, the deformation rates each being measured after a load is applied in the longitudinal direction of the magnetic tape for 96 hours.

The magnetic tape includes a non-magnetic support, and a magnetic layer including a ferromagnetic powder. The non-magnetic support is a polyethylene naphthalate support, and a deformation rate ratio of a deformation rate in a width direction to a deformation rate in a longitudinal direction of the magnetic tape, (the deformation rate in the width direction/the deformation rate in the longitudinal direction), is 0.42 or less, the deformation rates each being measured after a load is applied in the longitudinal direction of the magnetic tape for 96 hours.

Provided are: a magnetic recording medium including a non-magnetic support and a magnetic layer containing a ferromagnetic powder, in which the ferromagnetic powder is an ε-iron oxide powder, H.sub.0.2 of the magnetic recording medium is 5,000 Oe or more and 40,000 Oe or less at a measurement temperature of 25° C., and an inclination of H.sub.0.2 obtained from H.sub.0.2 at a measurement temperature of 10° C., H.sub.0.2 at a measurement temperature of 25° C., and H.sub.0.2 at a measurement temperature of 40° C. is −100 Oe/° C. or more and −5 Oe/° C. or less; a magnetic tape cartridge including the magnetic recording medium which is a magnetic tape; and a magnetic recording and reproducing device including the magnetic recording medium.

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.5μm-PSDmag/PSD.sub.10μm-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.

In the magnetic recording and reproducing device, a distal end width of the first magnetic pole in the recording element is substantially the same as a distal end width of the second magnetic pole; the reproducing element width of the reproducing element is equal to or less than 0.8 μm; and in the magnetic recording medium, a number distribution A of equivalent circle diameters of a plurality of bright areas in a binarized image of a secondary electron image obtained by imaging a surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 5 kV, and a number distribution B of equivalent circle diameters of a plurality of dark areas in a binarized image of a secondary electron image obtained by imaging the surface of the magnetic layer with a scanning electron microscope at an acceleration voltage of 2 kV satisfy predetermined number distribution, respectively.

A magnetic recording medium used on a record/playback device with a minimum recording wavelength or 50 nm or shorter, the magnetic recording medium including a magnetic layer that contains a spinel-type ferrite magnetic powder, the magnetic layer having an average thickness of 85 nm or smaller, and the magnetic layer having a saturation flux density of 1600 Gauss or larger and 2000 Gauss or smaller.

The magnetic tape in which a difference (S.sub.0.1−S.sub.1.6) between a spacing S.sub.0.1 and a spacing S.sub.1.6 obtained after n-hexane cleaning on a surface of the magnetic layer is equal to or less than 32 nm. The S.sub.0.1 is a value obtained as a spacing under a pressing force of 0.1 atm from a relational expression between a pressure and a spacing obtained by performing a spacing measurement on the surface of the magnetic layer by an optical interference method under a pressing force of each of a plurality of different pressures after the n-hexane cleaning, and S.sub.1.6 is a spacing measured on the surface of the magnetic layer by the optical interference method under the pressing force of 1.6 atm after the n-hexane cleaning.

In the magnetic tape, a magnetic tape deformation amount after storage for 3 months each in a predetermined environment is 0.50 μm or less, a rate of a change in the magnetic tape deformation amount with respect to a change in relative humidity is 0.0001 μm/% to 0.0500 μm/%, and a rate of a change in magnetic tape deformation amount with respect to a change in temperature is 0.0010 μm/° C. to 0.1000 μm/° C.

In the magnetic tape, in a case where a maximum value of an absolute value of a difference between a servo band spacing obtained before storage in an environment of a temperature of 32° C. and relative humidity of 55% and a servo band spacing obtained after storage in the environment for a storage time T is set to A, and T is defined as 24 hours, 48 hours, 72 hours, 96 hours, or 120 hours, a medium life calculated by a linear function of A and a logarithm log.sub.eT of T, that are derived from a value of A and a value of the logarithm log.sub.eT of T obtained for each T is 3 years or longer. The medium life is T in a case where the A satisfies Equation 1: A=1.5−B.

A magnetic tape in which an arithmetic average roughness Ra measured at a surface of the magnetic layer with an atomic force microscope is 2.0 nm or less, and in an environment with a temperature of 23° C. and a relative humidity of 50%, an AlFeSil abrasion value.sub.45° of a surface of the magnetic layer measured at a tilt angle of 45° of an AlFeSil prism is 20 μm to 50 μm, a standard deviation of an AlFeSil abrasion value of the surface of the magnetic layer measured at each of tilt angles of 0°, 15°, 30°, and 45° of the AlFeSil prism is 30 μm or less, and the tilt angle of the AlFeSil prism is an angle formed by a longitudinal direction of the AlFeSil prism and a width direction of the magnetic tape.