New series of solutions for space-times which are regarded as representing the gravitational fields of spinning bound masses is derived from a series of Weyl metrics, following Ernst's formulation on axi-symmetric stationary fields. This series of solutions includes the Kerr metric as a member of the simplest one. Except in the case of the Kerr metric, the space-times have ring singularities outside event horizons, that is, there exist naked singularities. Therefore, these solutions seem to give a very different picture concerning the ultimate fate of gravitational collapse compared with a current picture such as the Israel-Carter conjecture. The naked ring singularity may become an active energy source of gravitational wave, and yield many interesting phenomena in astrophysics.