A curable composition includes a curable resin and a magnetic body, wherein the magnetic body comprises magnetic particles and a surface treatment agent present on a surface of the magnetic particles. The curable composition has low viscosity, and fluidity, and capable of effectively cured without causing curing shrinkage or the like to form a cured product having desired physical properties.

A curable composition includes a curable resin and a magnetic body, wherein the magnetic body comprises magnetic particles and a surface treatment agent present on a surface of the magnetic particles. The curable composition has low viscosity, and fluidity, and capable of effectively cured without causing curing shrinkage or the like to form a cured product having desired physical properties.

Provided is a magnetic tape, in which, in an environment of a temperature of 23? C. and a relative humidity of 50%, an AlFeSil abrasion value.sub.45? of a magnetic layer surface measured at a tilt angle of 45? of an AlFeSil square bar is 20 ?m or more and 50 ?m or less, standard deviation of an AlFeSil abrasion value of the magnetic layer surface measured at each of tilt angles of 0?, 15?, 30?, and 45? of the AlFeSil square bar is 30 ?m or less. The tilt angle of the AlFeSil square bar is an angle formed by a longitudinal direction of the AlFeSil square bar and a width direction of the magnetic tape. A magnetic tape cartridge and a magnetic tape apparatus include the magnetic tape.

Provided is a magnetic tape, in which, in an environment of a temperature of 23 C. and a relative humidity of 50%, an AlFeSil abrasion value.sub.45 of a magnetic layer surface measured at a tilt angle of 45 of an AlFeSil square bar is 20 m or more and 50 m or less, standard deviation of an AlFeSil abrasion value of the magnetic layer surface measured at each of tilt angles of 0, 15, 30, and 45 of the AlFeSil square bar is 30 m or less. The tilt angle of the AlFeSil square bar is an angle formed by a longitudinal direction of the AlFeSil square bar and a width direction of the magnetic tape. A magnetic tape cartridge and a magnetic tape apparatus include the magnetic tape.

According to one embodiment, a magnetic recording device includes a recording medium, a magnetic head including a light source, a light emitting element, and a sensor, and a controller including an inspection circuit which detects a height of a defect of the recoding medium based on output of the sensor, a memory recording the height of the defect, and a setting circuit which sets an upstream side record/reproduce prohibited sector on an upstream side of the defect, in a travel direction of the magnetic head, on a track of the recording medium on which the defect is present, and which sets a downstream side record/reproduce prohibited sector longer in track direction than the upstream side record/reproduce prohibited sector on a downstream side of the defect.