A method of producing lipids, comprising the steps of: culturing a transformant in which the expression of a gene encoding at least any one of the following proteins (A) to (D) is enhanced in a cyanobacteria cell, and producing fatty acids or lipids containing these fatty acids as components. (A) a protein consisting of the amino acid sequence set forth in SEQ ID NO: 1; (B) a protein consisting of an amino acid sequence having 60% or more identity with the amino acid sequence of the protein (A), and having β-ketoacyl-ACP synthase activity; (C) a protein consisting of the amino acid sequence set forth in SEQ ID NO: 44; and (D) a protein consisting of an amino acid sequence having 60% or more identity with the amino acid sequence of the protein (C), and having β-ketoacyl-ACP synthase activity.