An anti-seismic device for seismically isolating a structure with respect to the ground comprising: - a first support defining a first support plane integrally connectable to an upper portion, for example to said structure , and comprising at least two first hinges defining a first constant reciprocal distance (d'), - a second support defining a second support plane comprising at least two second hinges defining a second constant reciprocal distance (d"), - a third support defining a third support plane integrally connectable to a lower portion, for example to said ground , and comprising at least two third hinges defining a third constant reciprocal distance (d′′′), and - connection means defining a connection plane perpendicular to said third support plane and comprising at least: - two first rigid bars , each defining a first non-deformable direction of connection and adapted to constrain said first support and said second support , and - two second rigid bars , each defining a second non-deformable direction of connection and adapted to constrain said second support and said third support , - said first bars each being transiently constrained to one of said first hinges and one of said second hinges so that said first directions of connection of said first bars cross in said connection plane , and - said second bars each being transiently constrained to one of said second hinges and one of said third hinges so that said second directions of connection of said second bars cross in said connection plane . - a first support defining a first support plane integrally connectable to an upper portion, for example to said structure , and comprising at least two first hinges defining a first constant reciprocal distance (d'), - a second support defining a second support plane comprising at least two second hinges defining a second constant reciprocal distance (d"), - a third support defining a third support plane integrally connectable to a lower portion, for example to said ground , and comprising at least two third hinges defining a third constant reciprocal distance (d′′′), and - connection means defining a connection plane perpendicular to said third support plane and comprising at least: - two first rigid bars , each defining a first non-deformable direction of connection and adapted to constrain said first support and said second support , and - two second rigid bars , each defining a second non-deformable direction of connection and adapted to constrain said second support and said third support , - two first rigid bars , each defining a first non-deformable direction of connection and adapted to constrain said first support and said second support , and - two second rigid bars , each defining a second non-deformable direction of connection and adapted to constrain said second support and said third support , - said first bars each being transiently constrained to one of said first hinges and one of said second hinges so that said first directions of connection of said first bars cross in said connection plane , and - said second bars each being transiently constrained to one of said second hinges and one of said third hinges so that said second directions of connection of said second bars cross in said connection plane . <EOS>