Disclosed is a method for suppressing the growth of a target cell, which is not limited in the type of a target cell and the type of a protein to be expressed in the target cell and needs not any preparatory experiment for determining a codon to be contained in a protein to be expressed in a target cell. Specifically disclosed is a method for suppressing the growth of a target cell, which comprises the steps of: incorporating DNA containing a region encoding a protein into the target cell, and allowing a protein encoded by the DNA to be expressed in the target cell into which the DNA has been incorporated. The region contained in the DNA comprises a tri-nucleotide sequence. The tri-nucleotide sequence is selected from codons that define at least some amino acid species constituting the protein, and is complementary to at least some codons that are used in the target cell at a frequency of 0.2 or less.
