Hidden Order and Exotic Superconductivity in the Heavy Fermion Compound URu2Si2 In this thesis the author investigates hidden order phase transition at T0 = 17.5 K in the heavy fermion URu2Si2. The four fold rotational symmetry breaking in the hidden order phase which imposes a strong constraint on the theoretical model is observed through the magnetic torque measurement. The translationally invariant phase with broken rotational symmetry is interpreted as meaning that the hidden order phase is an electronic “nematic” phase. The observation of such nematicity in URu2Si2 indicates a ubiquitous nature among the strongly correlated electron systems. The author also studies the superconducting state of URu2Si2 below Tc = 1.4 K which coexists with the hidden order phase. A peculiar vortex penetration in the superconducting state is found which may be related to the rotational symmetry breaking in the hidden order phase. The author also identifies a vortex lattice melting transition. This transport study provides essential clues to the underlying issue of quasiparticle dynamics as to whether a quasiparticle Bloch state is realized in the periodic vortex lattice