To provide a lubricant additive and a lubricant additive composition desirably used in e.g., a metal processing oil giving high rust-preventive properties to a variety of steel sheets and easily removed with an alkali degreasing solution and to provide a lubricant composition containing these and used as e.g., a metal processing oil.

Provided are a lubricant additive comprising a hydrolyzable organosilicon compound, a lubricant additive composition comprising a combination of (A) the lubricant additive with (B) a rust-preventing agent, and a lubricant composition comprising a base oil comprising a mineral oil and/or a synthetic oil and either the lubricant additive or the lubricant additive composition.