Coloring of fruits is promoted by applying a one or more the amino acids leucine, isoleucine, and/or phenylalanine, in combination with abscisic acid to a fruit plant, such as those of the genus Vitaceae or Rosaceae. The amino acid(s) and abscisic acid may be present in a solution(s) having concentrations of 0.2 mM to 100 mM and 0.1 μM to 10 mM, respectively.