The present invention relates to a compound represented by the formula (1)wherein Xa and Xb are each independently X1 or X2;s is 1 or 2,R4 is an alkyl group having 1-6 carbon atoms,na and nb are each independently 0 or 1,R1a and R1b are each independently an alkylene group having 1-6 carbon atoms,R2a and R2b are each independently an alkylene group having 1-6 carbon atoms,Ya and Yb are each independently an ester bond, an amide bond, a carbamate bond, an ether bond or a urea bond, andR3a and R3b are each independently a sterol residue, a liposoluble vitamin residue or an aliphatic hydrocarbon group having 12-22 carbon atoms,and use thereof.