1. A biological sample image acquiring apparatus comprising: an objective lens magnifying a region of a biological sample; an imaging device imaging the region magnified by the objective lens; a movement controller moving the focus of the objective lens in the thickness direction of the target region of the biological sample and moving the image of the region, which is magnified by the objective lens to be imaged onto the imaging device, in an in-plane direction; and a biological sample image acquiring unit acquiring a biological sample image of the region by exposing the imaging device to light while the movement controller is moving the image of the region.