A neutralization/water separation device for an esterified product, comprising: a neutralization tank in which a crude product mixture containing alcohol and an ester compound, a neutralizing agent, and water are put to produce a neutralized mixture; a water separation tank disposed below the neutralization tank to divide the neutralization mixture into a floating layer and an aqueous layer; a partition wall extending downward from a ceiling of the water separation tank to provide a lower passage in the water separation tank; and a transfer line connected to a bottom surface of the neutralization tank configured to transfer the neutralized mixture from the neutralization tank to the water separation tank, wherein the water separation tank comprises: a first water separation part into which the neutralized mixture is introduced from the neutralization tank through the transfer line; and a second water separation part into which the neutralized mixture is introduced from the first water separation part through the lower passage, wherein the first water separation part and the second water separation part are partitioned by the partition wall; wherein a bottom surface of the water separation tank is gradually inclined downward toward a center thereof; wherein the water separation tank is provided in plurality and the plurality of water separation tanks (12a, 12b) are connected in parallel to the neutralization tank. a neutralization tank in which a crude product mixture containing alcohol and an ester compound, a neutralizing agent, and water are put to produce a neutralized mixture; a water separation tank disposed below the neutralization tank to divide the neutralization mixture into a floating layer and an aqueous layer; a partition wall extending downward from a ceiling of the water separation tank to provide a lower passage in the water separation tank; and a transfer line connected to a bottom surface of the neutralization tank configured to transfer the neutralized mixture from the neutralization tank to the water separation tank, wherein the water separation tank comprises: a first water separation part into which the neutralized mixture is introduced from the neutralization tank through the transfer line; and a second water separation part into which the neutralized mixture is introduced from the first water separation part through the lower passage, wherein the first water separation part and the second water separation part are partitioned by the partition wall; wherein a bottom surface of the water separation tank is gradually inclined downward toward a center thereof; a first water separation part into which the neutralized mixture is introduced from the neutralization tank through the transfer line; and a second water separation part into which the neutralized mixture is introduced from the first water separation part through the lower passage, wherein the first water separation part and the second water separation part are partitioned by the partition wall; wherein a bottom surface of the water separation tank is gradually inclined downward toward a center thereof; wherein the water separation tank is provided in plurality and the plurality of water separation tanks (12a, 12b) are connected in parallel to the neutralization tank.