The present invention provides a gene transfer agent, a gene transfer kit, and a gene transfer method excellent in safety and transfer efficiency. Specifically, the present invention provides a gene transfer agent composition, the gene transfer agent composition including a compound represented by any one of the following formulae DL-G1 to DL-G4: DL-G1: R1R2NX(XH2)2 DL-G2: R1R2NX(X(XH2)2)2 DL-G3: R1R2NX(X(X(XH2)2)2)2 and DL-G4: R1R2NX(X(X(X(XH2)2)2)2)2 (X represents - CH2CH2CONHCH2CH2N-), in which: R1 represents an unsaturated long-chain aliphatic group and R2 represents an unsaturated long-chain aliphatic group or a saturated long-chain aliphatic group in the formulae.
