A position determining device for determining a position of a neighboring vehicle, comprising: a receiving unit configured to receive a first sensing signal related to the neighboring vehicle from a first ultrasound sensor installed in a vehicle and receive a second sensing signal related to the neighboring vehicle from a second ultrasound sensor installed at a position separated away from the first ultrasound sensor; a confirming unit configured to determine the receiving time and strengths of each of the first sensing signal and the second sensing signal, and wherein the confirming unit is configured to position each of the first sensing signal and the second sensing signal on a time-strength plane to thereby determine the receiving time and strengths of each of the first sensing signal and the second sensing signal; a determination unit configured to determine a first position of the neighboring vehicle on the basis of the receiving time and strengths of each of the first sensing signal and the second sensing signal, wherein the determination unit is configured to periodically determine a changing position of the neighboring vehicle on the basis of receiving time and strengths of each of the first sensing signal and the second sensing signal, wherein the determination unit is configured to periodically determine the changing position of the neighboring vehicle on the basis of periodically determined differences in the receiving time and strength of each of the first sensing signal and the second sensing signal, and wherein the confirming unit is configured to determine the difference in the receiving time and strength of each of the first sensing signal and the second sensing signal from a relative signal attenuation-time delay histogram which is generated with respect to one signal of the first and the second sensing signals on the basis of the other signal thereof on the time-strength plane. a receiving unit configured to receive a first sensing signal related to the neighboring vehicle from a first ultrasound sensor installed in a vehicle and receive a second sensing signal related to the neighboring vehicle from a second ultrasound sensor installed at a position separated away from the first ultrasound sensor; a confirming unit configured to determine the receiving time and strengths of each of the first sensing signal and the second sensing signal, and wherein the confirming unit is configured to position each of the first sensing signal and the second sensing signal on a time-strength plane to thereby determine the receiving time and strengths of each of the first sensing signal and the second sensing signal; a determination unit configured to determine a first position of the neighboring vehicle on the basis of the receiving time and strengths of each of the first sensing signal and the second sensing signal, wherein the determination unit is configured to periodically determine a changing position of the neighboring vehicle on the basis of receiving time and strengths of each of the first sensing signal and the second sensing signal, wherein the determination unit is configured to periodically determine the changing position of the neighboring vehicle on the basis of periodically determined differences in the receiving time and strength of each of the first sensing signal and the second sensing signal, and wherein the confirming unit is configured to determine the difference in the receiving time and strength of each of the first sensing signal and the second sensing signal from a relative signal attenuation-time delay histogram which is generated with respect to one signal of the first and the second sensing signals on the basis of the other signal thereof on the time-strength plane.