1. An X-ray computer tomography apparatus comprising: an X-ray source which emits X-rays; an X-ray detector which has a plurality of detection elements configured to detect X-rays transmitted through an object to be examined; a scanogram generating section which generates a scanogram in a first direction of the object on the basis of an output from said X-ray detector; a distribution information generating section which generates distribution information of X-ray absorptances or absorbed X-ray doses in the first direction of the object by dividing the scanogram into matrixes and calculating X-ray absorptances or absorbed X-ray doses on a matrix basis; an imaging condition determining section which determines an imaging condition on the basis of the distribution information; and a controller which controls computer tomography of the object on the basis of the imaging condition.