An axle driving unit having a housing including at least two housing parts joined to each other through a joint surface, at least one of the housing parts including a recess formed in a wall thereof. The axle driving unit further includes a pair of hydraulic devices mounted perpendicular to each other on corresponding mounting surfaces of a center section. The center section further includes a portion extending outwardly parallel to the joint surface, the portion being fitted into the recess of the housing part.