Novel amidine derivatives of the formula (1); and drug carriers such as liposomes or emulsions comprising the derivatives, which can enclose genetic materials or drugs and transfer them to cells or affected sites efficiently and safely, wherein A is an aromatic ring, R1 and R2 are the same or different and independently represent an alkyl group having any one of 10 to 25 carbon atoms, and an alkenyl group having any one of 10 to 25 carbon atoms, X and Y are the same or different and independently represent —O—, —S—, —COO—, —OCO—, —CONH—, or —NHCO—, m is 0 or 1, and n is 0 or a natural number of 1 to 6.