Provided is a robot cleaner including a main body including a suction portion disposed thereon, main wheels for moving the main body, a side brush assembly disposed on the main body and rotating with a rotation shaft perpendicular to a rotation shaft of the main wheels, wherein the side brush assembly includes a housing for forming an exterior of the side brush assembly, a first force transmitter disposed in the housing and rotating by receiving a driving force, a second force transmitter in contact with the first force transmitter to rotate together when the first force transmitter is rotated, and a side brush coupled to the second force transmitter to rotate at the same rotation angle as the second force transmitter.