In a vehicular final speed reducing device, the intermediate, rear, bottom and the side walls define a breather chamber, and the partition wall divides the breather chamber into auxiliary and primary breather chambers. The auxiliary breather chamber is held in communication with a space outside the breather chamber and within the housing, through a first hole formed through the intermediate wall, and through an opening formed between the intermediate and bottom walls. The primary breather chamber is held in communication with an outside atmosphere outside the housing, and with the auxiliary breather chamber through a second hole formed through the partition wall. The bottom wall extends from the rear wall such that a front end of the bottom wall is located forwardly of the opening in the axial direction of the ring gear.