New half-metallic ferromagnets have been found in a zinc-blende crystal structure. The zinc-blende CrAs has been designed by ab initio calculations and the calculation predicts the highly spin-polarized electronic band structure. The zinc-blende CrAs thin film has been synthesized on GaAs (001) substrates by molecular-beam epitaxy. The film shows ferromagnetic behavior at room temperature and the magnetic moment per formula unit of CrAs is estimated to be about 3 μ_B, which agrees well with the theoretical prediction. The photoemission spectra of the CrAs film showed the Fermi edges indicating the metallic characteristics and the small band dispersion derived from Cr-3d bands.