The aim of the paper is to present and stress the role of Cartesian metaphysics in establishing the bases of modern physics. It is usually undervalued, that the originality of Cartesian idea rests on the fact that the French philosopher approaches metaphysics not traditionally, as a theory of reality, but as a theory referring to the bases of physics, being is fact the theory of reality itself. In this perspective, such basic metaphysical issues as the problem of God or soul receive completely untraditional sense. In Cartesian system God is necessary not as a base of reality but as a guarrantor of truthfulness of our geometric, mechanistic knowledge of the world. The soul, however, if it indeed is a serious issue here, it is certainly not because of its immortality or substantial separation from the body but only as mind which is a place of formation of the above-mentioned picture of reality. Definitely, however, more important issue for the philosophy of physics is the problem of God and God's veracity. Referring the theological argument while searching for bases of veracity of physical recognition Descartes created not as much positive metaphysical idea as he rather gave an expression of his deep doubts in the question of certitude and veracity of physics, doubts which couldnot be cancelled by modern physics. At least this look at his philosophy seems to be at least more interesting from today's point of view.