Of various Fol-PEG-GUG-β-CDEs (G3, DSC3.7, DSF3.9, 6.7, and 7.3, DSP3.9, 6.7, and 7.3), Fol-PEG-GUG-β-CDE (G3, DSC3.7, DSF6.7, DSP6.7) showed the highest siRNA transfection activity at a charge (N/P) ratio of 50 (carrier/siRNA) in both 786-0-luc cells (FR-α (+)), a luciferase stably expressing human renal cancer cell line, and KB cells (FR-α (+)). The gene discussed is FOLR1; the disease is renal carcinoma.