Spin transport in molecular systems has been attracting much attention, because a weak spin-orbit interaction in molecules allows us to expect good spin coherence. Although spin injection and spin transport in molecules were not easily achieved at room temperature, graphene, which is one of the most attractive materials in condensed matter physics since 2004, provided an ideal platform to realize and discuss spin injection and transport at room temperature. We present our study on spin injection into graphene and important findings of unique spin transport properties in graphene.