Disclosed herein is a washing machine, which includes a clutch unit provided to be able to selectively transmit power generated from a drive unit to a drum and a pulsator. The clutch unit includes an outer shaft that is connected to the drum at an upper side thereof and rotates the drum, an inner shaft that is located in the outer shaft, is connected to the pulsator at an upper side thereof, and rotates the pulsator, and a one-way bearing that is installed between the inner shaft and the outer shaft. The one-way bearing selectively transmits a rotating force from the outer shaft to the inner shaft according to a rotating direction of the outer shaft. With this configuration, it is possible to simplify a structure of the clutch unit and to use space efficiently.