Abstract: Aerogenerator blade and method of manufacturing thereof, the aerogenerator blade comprising an intrados shell, an extrados shell and a structural beam, the structural beam comprising a root spar, a transitional spar and a box spar, wherein the root spar has a substantially circular cross section configured to support the connection of the blade to the aerogenerator hub; the transitional spar tapers from the root spar towards the box spar; and the box spar tapers towards the blade tip; and wherein the aerogenerator blade is characterized by comprising: a first section of the structural beam including at least a root spar portion, a transitional spar portion and a box spar portion, the portions forming a first integral structural beam section; a second section including at least the counterparts of the root spar portion, the transitional spar portion and the box spar portion, said counterpart portions forming a second integral structural beam section; and wherein the first section of the structural beam is join