A quinone compound of the formula: ##STR1## wherein R stands for an alkyl group of 1 to 22 carbon atoms having at its terminal end a hydroxyl group which may be protected, can be obtained with industrial advantage by allowing a compound of the formula: ##STR2## to react with a peroxide of a carboxylic acid of the formula: RCOOH wherein R is as defined above, or with a peroxide of an acid anhydride of the carboxylic acid. The quinone compound wherein R stands for an alkyl group of 1 to 2 carbon atoms having at its terminal end an optionally protected hydroxyl group, is a novel compound and has antifibrotic activity.