An automatic dual bobbin mechanism is provided. A housing containing two unique bobbin casings and bobbins therein oriented side-by-side with the sewing needle and thread passing between the bobbin casing pair replaces the convention single bobbin configuration. The bobbin pair acts in a tag-team operation whereby one bobbin supplies thread to be stitched into a fabric while the second bobbin is simultaneously filled with thread from an external source. When the first bobbin is emptied, the bobbin pair is rotated 180.degree. inside the housing. The second bobbin, now full, supplies thread for continued stitching while the first bobbin is refilled with thread supplied by the external source. The specially designed bobbins and bobbin casings allow for automatic rethreading of the empty bobbin and cutting of the bobbin thread from external source, thus eliminating the need to manually remove the empty bobbin and assembly, replace with a full bobbin and rethread.