The LaAlO3/SrTiO3 heterointerface has been discovered to show two-dimensional interfacial conductivity and other intriguing emergent phenomena. Its interfacial conductivity was mainly characterized by electric methods previously. Here the authors present for the first time that scattering-type scanning near-field optical microscopy (s-SNOM) can be employed to spatially image the conductivity of the buried LaAlO3/SrTiO3 interface, providing a new means to study the physics of transition metal oxide heterointerface systems.