1. An object detection apparatus for detecting objects in input images captured from a mobile unit, comprising: a local flow processor for calculating flow information for each local area in said input images; a global flow processor for calculating flow information for each global area in said input images using said flow information for each local area; a flow feature calculator for estimating motion of the mobile unit using said flow information for each global area, calculating new flow information using the estimated motion, comparing said new flow information with said flow information for each local area to extract local areas having flow information not consistent with said estimated motion; and an object presence/absence determiner for determining the presence or absence of objects in the extracted local areas.