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, and R3a 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.