An automatic charging station for an autonomous mobile machine includes a base, a housing, and a signal transmitter. The base is mounted on the ground or on a planar surface. The housing is rotatably mounted on the base, having at least one guide member and a plurality of electrically conductive members on a surface thereof. The electrically conductive members are located on the housing. The signal transmitter is mounted on the housing for transmitting a signal. When the autonomous mobile machine senses the signal transmitted by the transmitter while moving, the autonomous mobile machine moves along a route towards the housing and then forces the guide member to enable the housing to rotate for facing and accommodating the autonomous mobile machine and to further enable the autonomous mobile machine to contact against the housing to have its electrodes in contact with the electrically conductive members for charging.