By improving the rigidity of a pulley while suppressing a weight of the pulley from increasing, excessive noises due to resonance can be reduced. A washing machine 1 includes a drum 9 rotatably disposed in the water tub 5. The washing machine 1 has a motor to rotationally drive a pulley 20, which is fixed to the drum 9, via an endless belt 13. The pulley 20 has a plurality of arms 23 radially extend from the boss 22 to support an outer wheel 21. The arm 23 has a variable cross-sectional portion 24 in which a section modulus against bending in an axial direction gradually decreases from the boss 22 to the outer wheel 21.
