A new three-dimensional (3D) hydrocarbon is proposed as a model of organic ferromagnets. This compound is the 3D-carbon-atom network composed of the benzen rings and the bridging carbon atoms with the itinerant pi electrons and the nonbonding electrons. This pi-electron system is studied within the Kondo-Hubbard model with the interlayer-transfer energy using a mean-field theory and periodic boundary conditions. The total energy the energy bands, and the spin densities have been computed. The amplitude of spin density at the bridging carbon atom is most largest. As a result, the spins at the bridging carbon atoms align ferromagnetically in the 3D directions. It turns out that the ferromagnetic ground state is stabilized than the nonmagnetic one through the antiferromagnetic correlation, the ferromagnetic exchange interaction and the topological structure of this compound.