Ultrasonic object detection device

An ultrasonic object detection device comprising:

• a first echo prolongation determination unit that sequentially determines whether a measured echo time, which is a duration of an echo sound to be detected by an ultrasonic sensor after the ultrasonic sensor transmits a transmission wave, is prolonged with respect to a reference echo time;
• a second echo prolongation determination unit that determines whether an addition echo time is prolonged with respect to the reference echo time when the first echo prolongation determination unit determines that the measured echo time is not prolonged with respect to the reference echo time, and the ultrasonic sensor detects a reflected wave generated by reflection of the transmission wave on an object, the addition echo time being obtained by adding, to the measured echo time, a time which elapses after an echo is terminated in a receiving signal of the ultrasonic sensor before a first reflected wave as the reflected wave generated for a first time is terminated;
• and
• a short distance object detection unit that determines that an object is disposed within a short distance so as to receive the reflected wave while the echo is not terminated when one of the measured echo time or addition echo time is prolonged with respect to the reference echo time.