Inflation plays an essential role in modern cosmology. It solves cosmological issues such as the horizon problem and provides a seed of cosmic microwave background (CMB) anisotropies and galaxy structures. However, the nature of a scalar field that causes inflation, or inflaton, is yet to be understood, and this is a big open question in particle cosmology.
In this talk, after reviewing the basics of inflation, I ask the question: whether the Higgs boson, discovered at the Large Hadron Collider, can be the origin of cosmic inflation. I show that, even though the Higgs cannot be the origin of inflation by itself, the Higgs can play the role of the inflaton with the help of a scalar graviton, or the scalaron. This scenario can be tested by future CMB observations such as CMB-Stage4 and LiteBIRD, providing an exciting opportunity to connect our understanding of particle physics and the very early stage of the universe.