A flywheel kinetic accumulator provides an accumulator assembly, in which a flywheel that is mounted on roll bearings rotates about a rotation axis; the flywheel is axially supported by two sets of magnetic elements (16, 16′) facing each other, arranged in two parallel planes, along two circular paths having the same diameter; one set is connected to the accumulator assembly, and the other to the flywheel; the magnetic elements (16, 16′) of the two sets are arranged in rotation, such that when a magnetic element (16) of the one set is aligned with a respective magnetic element (16′) of the other set along an axis that is parallel to the rotation axis, all other magnetic elements (16, 16′) are offset with respect to one another in order to reduce/eliminate the magnetic forces acting in the direction opposite to the rotation direction (V).