PURPOSE: To improve surface smoothness, mechanical strength, wet heat resistance, and resilience at a low temp. by incorporating a polyurethane resin formed by bringing a polyhydroxy compd. for at least a part of which specific compds. are used and a polyisocyanate compd. into a binder.

CONSTITUTION: The binder for the magnetic recording medium contg. the polyurethane resin formed by bringing the polyhydroxy compd. having ≥2 pieces of active hydrogen atoms in the molecule and the polyisocyanate compd. into reaction is formed. The constitutional unit of at least a part of this polyhydroxy compd. consists of at least two kinds of the constitutional units selected from the constitutional units (I) to (IV) expressed by formula I to IV. The contents thereof are 90/10 to 20/80 molar ratios of [(I)+(III)]/[(II)+(III)] and 50/50 to 0/100 molar ratios of [(III)+(TV)]/[(I)+(II)]. The respective constitutional units are polyester carbonate polyols forming ester bonds or carbonate bonds with each other.