It has been known that a naive computation of loop corrections in inflationary universe gives rise to a pathologically large enhancement of the infrared (IR) contributions. In this talk, I will overview the recent progress on the IR issues during inflation. In particular, for the adiabatic and tensor perturbations, we can show that the IR pathology goes away, as far as we preserve the invariance under the large gauge transformations, which diverge at the spatial infinity. I also show a couple of other consequence of the invariance under the large gauge transformation; 1) the consistency relations, which connect (n+1)-point functions with one soft leg and n-point functions 2) the conservation of the curvature perturbation at large scales in the presence of the radiative corrections of heavy fields.