An imaging apparatus which has two imaging units, comprising: a correlation value calculation unit that calculates a correlation value from two images captured by the two imaging units; a three-dimensional object detection unit that detects a three-dimensional object from the two images; a region dividing unit that divides an image region including the three-dimensional object into multiple regions; a relative speed calculation unit that calculates relative speed for every region of the multiple regions; and a reliability calculation unit that calculates reliability of the three-dimensional object, based on the relative speed calculated for every region; the imaging apparatus, further comprising: a feature amount calculation unit that calculates a feature amount from an image including the three-dimensional object detected by the three-dimensional object detection unit; and a matching degree calculation unit that calculates a matching degree of the feature amount between a past feature amount which is stored and a current feature amount which is calculated, wherein the relative speed calculation unit calculates the relative speed, based on the calculated matching degree wherein the relative speed for each region is obtained on the basis of a determined position of each region wherein the reliability calculation unit calculates reliability of whether or not the three-dimensional object moves, either based on a matching degree of the relative speed calculated for every region or based on the matching degree of the feature amount; wherein the relative speed calculation unit calculates the relative speed by selecting a frame in which the matching degree of the feature amount is highest from the past frames which are stored. a correlation value calculation unit that calculates a correlation value from two images captured by the two imaging units; a three-dimensional object detection unit that detects a three-dimensional object from the two images; a region dividing unit that divides an image region including the three-dimensional object into multiple regions; a relative speed calculation unit that calculates relative speed for every region of the multiple regions; and a reliability calculation unit that calculates reliability of the three-dimensional object, based on the relative speed calculated for every region; a feature amount calculation unit that calculates a feature amount from an image including the three-dimensional object detected by the three-dimensional object detection unit; and a matching degree calculation unit that calculates a matching degree of the feature amount between a past feature amount which is stored and a current feature amount which is calculated, wherein the relative speed calculation unit calculates the relative speed, based on the calculated matching degree wherein the relative speed for each region is obtained on the basis of a determined position of each region wherein the reliability calculation unit calculates reliability of whether or not the three-dimensional object moves, either based on a matching degree of the relative speed calculated for every region or based on the matching degree of the feature amount; wherein the relative speed calculation unit calculates the relative speed by selecting a frame in which the matching degree of the feature amount is highest from the past frames which are stored.