1. An image pick-up apparatus for picking up an image of object, the image pickup apparatus comprising: image pick-up means having a light receiving surface for receiving light from the object to carry out photo-electric conversion, and adapted to output pixel value obtained as the result of the photo-electric conversion; evaluating means for evaluating the pixel value; and control means for controlling, in pixel units, exposure time with respect to the light receiving surface on the basis of evaluation result by the evaluating means.