An agitator and a robot cleaner including an agitator. The agitator includes a body configured to be rotated, a plurality of couplers formed at the body and arranged to be spaced apart from each other by a predetermined distance, and a first member and a second member coupled to any one of the couplers and configured to contact a surface to be cleaned during rotation of the body. The first member and the second member extend different lengths from the body in a radial direction.