An overhead scanner device includes an area sensor, a linear sensor, and a control unit, wherein the control unit includes an area-image acquiring unit that controls the area sensor to successively acquire a plurality of images, a feature-point extracting unit that extracts feature points from the images acquired by the area-image acquiring unit, a velocity-vector computing unit that computes a velocity vector of each of the feature points by comparing the feature points extracted by the feature-point extracting unit between the images, and a read-start determining unit that determines a read start by the linear sensor, based on the velocity vector computed by the velocity-vector computing unit.