A foundation for wind turbine towers of the type used to support both metal towers and concrete towers of wind turbines that uses precast concrete or metal beams, combined with small footings concreted in situ, the beams being structurally connected at the central part of the foundation by the elements of connection and of support of the tower is disclosed. The invention affords the main advantage of achieving a notable reduction in the volume of materials used, both concrete and rebar, with a great reduction in assembly time and the consequent great economic savings as well as its ease of adaptation to different terrains is presented.