The present disclosure is directed to providing: a new cell-penetrating peptide; and a composition for delivering a biologically active substance, a composition for gene therapy, a method for delivering a biologically active substance and a method for gene therapy using the same. The cell-penetrating peptide of the present disclosure can effectively deliver a protein into human cells and tissues, can deliver a protein with higher efficiency in comparison with a TAT peptide that is commercially used as a cell-penetrating peptide, and can also be usefully used in delivering a biologically active substance such as a protein, a genetic material, a chemical compound, etc. which may be used for a therapeutic purpose into cells.