A washing device for washing a portion of a user's head includes a discharge section which discharges a cleaning liquid into a washing cap attached to a portion of a user's head, and a recovery section which drains the cleaning liquid out of the washing cap so as to recover it. The device again discharges the cleaning liquid recovered by the recovery section from the discharge section, and recirculates the cleaning liquid so as to wash the portion of the user's head covered by the washing cap. When the cleaning liquid is dispersed into the washing cap, the cleaning liquid passes through a nozzle unit so that a lot of microbubbles are generated in the cleaning liquid. The microbubbles are very fine air bubbles, and can remove fine particles of dirt down to the order of a few microns but do not damage the user's scalp and hair.