PURPOSE: To prevent oil stain and contamination of rolling mill lubricant by the lubricating oil leaking from the supporting rolls in the final stage by incorporating a circulation system for the feeding system of the rolling mill lubricant and using the lubricant of the supporting rolls in the final stage as the base oil for the rolling mill lubricant.

CONSTITUTION: The rolling mill lubricant prepd. by mixing the base oil, additive and water supplied respectively from tanks 20, 22, 23 to an emulsified liquid in a tank 24 is sprayed to a rolled material and work rolls 1, etc. by a pump 25. Such lubricant is collected in a collector 27 and is returned to the tank 24 so as to be cyclically used. The base oil is forced from the tank 20 by a pump 21 to the supply passage 11 in the stationary shaft 6 of supporting rolls 3 in the final stage so that the oil is functioned as a lubricant for the rolling bearing parts via rollers 8 between the inner and outer rings 7 and 9 of the rolls 3. The base oil is thereafter returned through a discharge passage 12 to the tank 20. The seizure and deterioration of the rolls 3 are thus prevented and even if the base oil leaks and falls onto the collector 27, the contamination of the rolling mill lubricant is obviated as said oil consists of the same principal component as that of the rolling mill lubricant.