Magnetic recording medium

A magnetic recording medium composed of an oriented polyethylene terephthalate film as a support layer and a thin magnetic metallic layer formed on one surface (A) of the support layer and optionally a lubricant layer formed on the other surface (B) of the support layer;

• characterized in that
• (1) the surface A has a center-line average (CLA) of not more than 0.005 .mu.m,
• (2) the surface A has a peak-to-valley (PV) value of not more than 0.06 .mu.m,
• (3) the number of protrusions having a height of 0.27 to 0.54 .mu.m on the surface A is at most 0.2 per mm.sup.2, and
• (4) the surface A is substantially free from protrusions having a height larger than 0.54 .mu.m,
• and wherein the oriented polyethylene terephthalate film support layer is produced by subjecting a lower alkyl ester of a dicarboxylic acid comprising terephthalic acid as a main component and a glycol comprising ethylene glycol as a main component to an ester-interchange reaction in the presence of, as a catalyst, a compound of at least one metal selected from Mn, Zn, Ca and Mg using a glycol solution of a trialkyl phosphate as a stabilizer wherein the concentration of phosphorus in the glycol solution is such that the amount of potassium hydroxide required to titrate the solution to a pH of 9.5 is expressed by the following formula:
• ##EQU4## wherein (P) is the amount (moles) of phosphorus in the glycol solution titrated, and (KOH) is the amount (moles) of potassium hydroxide required to the titration,
• polycondensing the ester-interchange reaction product, extruding the resultant polyethylene terephthalate, stretching the resulting film, and heat-setting the stretched film.