Abstract: Disclosed is a power transmission device.

Abstract: A power transmission device is disclosed. The power transmission device may include a power portion including a power generating portion including a power source generating power, and a fixing portion extending from the power generating portion in an axial direction, a driving member operatively connected to the power source and including a driving gear, a driven member including a driven gear engaged with the driving gear, a rotating member coupled to the driven member and rotating with the driven member, and an output member having a rotating wheel mounted thereon, defining an axial width, coupled to the rotating member, and rotating with the rotating member, the power source may include a power source shaft, and the power source shaft may be disposed in a range of ?25° to 25° with respect to a radial direction of a rotating wheel.