A method of producing lipids, containing the steps of: culturing a transformant in which the expression of a gene encoding the following protein (A) or (B) is enhanced, and producing long-chain fatty acids or the lipids containing these fatty acids as components, wherein: protein (A) is a protein consisting of the amino acid sequence set forth in SEQ ID NO: 1; and protein (B) is a protein consisting of an amino acid sequence having 70% or more identity with the amino acid sequence of the protein (A), and having β-ketoacyl-ACP synthase activity.