An obstacle detection device controls distance sensors to cause the distance sensors to transmit a transmission wave during a fixed time period, measures a first time which has elapsed from a time at which the transmission starts to a time at which a reflected wave is detected, and a second time which has elapsed a time at which the above-mentioned transmission is stopped to a time at which the reflected wave disappears, and determines that an obstacle exists when a time difference between the above-mentioned first time and the above-mentioned second time is equal to or shorter than a predetermined allowed time. Therefore, the obstacle detection device can reduce the time required for the determination to at least one-half that provided by a related art technique, and improves the accuracy of the detection of an object moving at a relatively high speed.