Abstract: Each blade of a turbomachine rotor is secured to the drum of the rotor by upstream and downstream legs on the radially inner side of the blade platform cooperating with upstream and downstream annular beads on the periphery of the durm, and a locking plate holding the legs in position. The end of the upstream leg is received in an annular groove in the upstream bead, and the downstream leg has an aperture which receives a tongue projecting from a collar on the downstream bead. the downstream leg ends in a cylindrical bearing surface acting on a cylindrical bearing surface of the drum, and includes two hooks on its donwstream face. The locking plate is located in an annular groove of the drum at the downstream edge of the cylindrical bearing surface and has first tongues engaging with the hooks on the downstream leg and second locating tongues at each end.