A robot cleaner is provided, including a main body forming a robot cleaner exterior, a driver coupled to the main body to move the main body, a cleaning module coupled to the main body to suck dust from a traveling surface, a dust collector removing dust from air suctioned through the cleaning module, and a wet-mop module coupled to the main body to mop the traveling surface, wherein the wet-mop module includes a wet-mop module housing surrounding at least a portion of the main body and accommodating water in an internal space, a wet-mop module wheel disposed in the wet-mop module housing, a mop disposed between the wet-mop module housing and the traveling surface, and a wet-mop pump connected to the wet-mop module wheel to supply water to the mop in response to rotation of the wet-mop module wheel. Mopping may be performed without applying physical force of a person.