A power supply device for a rotary distance detection device of a robot vacuum cleaner includes a base having a control board which is electrically connected to a power supply so as to control the base to move. The control board has bearings and a distance-detection circuit board on the bearings. The distance-detection circuit board is electrically connected to the control board and the power supply via the bearings so that the robot vacuum cleaner is able to work continuously without worry of replacement of batteries.