A system and a method for motion estimation are disclosed. The system for motion estimation in accordance with an embodiment of the present invention includes: a plurality of motion sensors mounted near joints of a body and configured to provide motion information; a depth sensor configured to provide 3-dimensional image information having a 3-dimensional coordinate for each pixel; and a motion estimation device configured to estimate a motion by use of the motion information and the 3-dimensional image information, wherein the motion estimation device includes: a converging unit configured to compute mounting position information of the motion sensors by performing an initialization process by converging the motion information and the 3-dimensional image information; and an estimating unit configured to estimate the motion by computing a state vector including the mounting position information and the motion information.