A lubricant base oil which contains an ester. The ester constituting the lubricant base oil includes: a component (A) derived from pentaerythritol in a molar percentage Amol % of 20 to 30 mol %; a component (B) derived from a straight-chain fatty acid having a carbon number of 14 to 22 in a molar percentage Bmol % of 55 to 79 mol %; and a component (C) derived from adipic acid in a molar percentage Cmol % of 1 to 15 mol %. A molar ratio (Cmol/Cmol) of the component (C) derived from adipic acid and the component (B) derived from the straight-chain fatty acid having a carbon number of 14 to 22 is 0.02 to 0.25, and the ester has a hydroxyl value of 10 to 100 mgKOH/g.