Abstract: An obstacle determination device mounted on an own vehicle determines whether the state of the own vehicle is a state immediately after progressing or a normal travel state ;selects, as a distance threshold provided to determine a non-obstacle, a starting distance threshold if in the state immediately after starting, or a normal distance threshold if in the normal travel state; extracts obstacle candidates on the basis of the result of comparison of the distance at which an obstacle candidate was initially detected with the distance threshold; selects a starting reflection intensity threshold if the state immediately after starting ,or a normal reflection intensity threshold if in the normal travel state; excludes non-obstacles on the basis of the result of comparison of the reception strength of the reflection wave of the remaining obstacle candidates with the reflection intensity threshold; and outputs the remaining obstacle candidates as obstacles.