抄録
D. Hilbert raised the problem to prove consistency of formalized mathematics. In this paper I will expound its background and the status quo of the consistency proofs. First let me explain the intended significance of proving consistency, and a background idea to divide mathematical objects in two, i. e., transfinite/finitary objects. Next I will discuss impacts of the incompleteness theorems to the problem and their interpretation. Finally let me give sketches of the practice of the consistency proofs due to G. Gentzen et al. and their significance, and the present state of the consistency proofs.
