To obtain a lubricant for making a hole in a substrate, having excellent adhesion, being excellent in a heat removal effect and a lubrication effect during making the through-hole and in the effect of preventing cuttings from being spattered, and being capable of making the through-hole with a good hole shape, and to provide a lubricating sheet using the lubricant and used for forming a hole in a substrate.

The lubricant is the one essentially consisting of an acid-group- containing polymer and/or a neutralization salt thereof, wherein the acid values of the polymer and/or the neutralization salt (the acid value is determined on the assumption that the salt is reconverted into a free acid) are each 3 mgKOH/g or higher. The lubricating sheet has a lubricant layer made from the lubricant.