Magnetic recording medium and manufacturing method therefor

A method of manufacturing a magnetic recording medium, comprising:

• a coating step for forming a magnetic layer by coating the surface of a non-magnetic support member with a magnetic coating material mainly composed of ferromagnetic powder and a polymer material and by drying the magnetic coating material;
• a step for flattening and smoothing the surface of said magnetic layer;
• a cutting step for manufacturing a magnetic disc by punching, into a disc shape, said non-magnetic support member having said magnetic layer formed thereon;
• and
• a heat treatment step for performing heat treatment of said magnetic disc at temperatures higher than a glass transition point of said polymer material and lower than a glass transition point of said non-magnetic support member, wherein
• said non-magnetic support member is a biaxially-oriented polyethylene terephthalate film having two main surfaces, difference Δn1 between refractive indexes of which is 1×10−3 or smaller, the thickness of said non-magnetic support member is 30 μm or greater and a coefficient of thermal contraction of said non-magnetic support member at 80° C. is 0.1% or lower,
• said magnetic coating material contains thermosetting polyisocyanate, and
• the heat treatment in said heat treatment step is performed under a temperature condition of 50° C. to 90° C.