An electric hub unit includes a hub composed of first casing and a second casing. An electric unit is located between the first and second casings. An axle extends through two respective centers of the first and second casings. The first casing has a reception recess defined in one side thereof. A first extension and a second extension extend axially from the first casing and toward in opposite directions. A bearing is located in the inside of the second extension. A socket unit has a tubular portion and a ratchet unit is connected to the socket unit. The socket unit is mounted to outside of the first casing, and a bearing and a plate are located between the tubular portion and the first extension. The hub unit prevents water and foreign objects from entering into the hub.