Hub unit for electric assistant man-powered vehicle

To enable adoption of a high-rotation and small-sized electric motor by adopting a high speed-reduction mechanism and further to efficiently reduce a diameter of a hub unit for an electric power-assisted human powered vehicle as a whole, the hub unit including at speed-reduction mechanism portion and a speed-change mechanism portion which are housed inwardly in a radial direction of the electric motor. A speed-reduction mechanism portion 5 includes: a speed-reduction sun gear 51 connected to a rotor 44 of an driving electric motor 4; a stationary speed-reduction ring gear 52 protruding from a motor case 41; a speed-reduction output ring gear 53 protruding from a hub case 2 inwardly in a radial direction of the stationary speed-reduction ring gear 52; a speed-reduction carrier 54; and a speed-reduction pinion 57 coaxially including a first gear 55 meshing with the speed-reduction sun gear 51 and the stationary speed-reduction ring gear 52 and a second gear 56 meshing with the speed-reduction output ring gear 5