"Inflation can be caused by the potential energy of a scalar field. Such a potential must be relatively flat in order to guarantee long duration of inflation and small deviation of scale invariance of primordial density fluctuations. However, the flatness of the scalar potential can be easily destroyed by radiative corrections. One of the leading theories to protect a scalar field from radiative corrections is supersymmetry (SUSY), which also gives an attractive solution to the (similar) hierarchy problem of the standard model (SM) of particle physics as well as the unification of the three gauge couplings. In particular, its local version, supergravity, would govern the dynamics of the early Universe, when high energy physics was important. Thus, it is quite natural to consider inflation in the framework of supergravity. However, in fact, it is a non-trivial task to incorporate inflation in supergravity. This is mainly because a SUSY breaking potential term, which is indispensable to inflation, generally gives a would-be inflaton an additional mass, which spoils the flatness of an inflation potential ..."