Abstract: The present invention relates to a drive device (1) for the assisted driving of a bicycle (2), which comprises an electric motor (3) and a driven shaft (6) that can be coupled to a traction mechanism drive (7) of the bicycle (2), wherein a planetary gear set (10) of the drive device (1) drive-connects a motor shaft (4) of the electric motor (3) with the driven shaft (6). A compact and cost-effective construction as well as an improved drive transmission of the drive device (1) materialise in that at least one sun gear (11), one internal gear (15) and one planet gear carrier (16) of the planetary gear set (10) are rotatably mounted about a common axis of rotation (17) in the planetary gear set (10). Further, the invention relates to a bicycle (2) having such a drive device (1).