In distribution systems, a large amount of photovoltaic systems (PVs) is being introduced, which may make the voltage profile more complicated. In order to accommodate PVs as much as possible, more advanced voltage management scheme should be developed. For such purpose, online voltage profile monitoring would be helpful. however, it needs installation of many sensors into the distribution system. On the other hand, smart meters and IT switches are being installed in Japan. That is, the distribution systems are being rich-information circumstances. Based on the above recent trend, this paper proposes voltage profile estimation methods based on the state estimation technique. The numerical case studies for the distribution network model with 2,160 consumers were carried out to validate the estimation performance.