Abstract: The invention relates to a device for controlling the blades of a wind turbine. According to the invention, each blade (7) is associated with means enabling same to rotate about the longitudinal axis thereof in order to: alter the angle of attack of the blades (7) in relation to the wind and select the power required, while maintaining a constant rotor speed; or stop the blades (7) when a pre-established rotation speed is exceeded. The invention is characterised in that the above-mentioned rotation means include: an electric motor (11) having an electronically-variable speed, a hydraulic pump/motor (10) included in a standard hydraulic circuit (1), and control means (12) for rotating the blades (7) using the electric motor (11) and the hydraulic pump/motor (10) in the presence of a power supply and for rotating the blades (7) using only the emergency and safety control module (4) and the emergency and safety hydraulic accumulator (5) in the absence of a power supply.