5-nm thick Co4N layers capped with 3-nm thick Au layers were grown epitaxially on SrTiO3(001) substrates by molecular beam epitaxy using solid Co and a radio-frequency NH3 plasma. Spin and orbital magnetic moments of the Co4N layers were estimated using x-ray magnetic circular dichroism (XMCD) measurements at 300 K. The site-averaged Co 3d spin magnetic moment is evaluated to be about 1.4 μB, which is smaller than that predicted theoretically (1.58 μB). The element-specific XMCD intensities for the Co L3 edge and N K edge show that the magnetic moment is induced at the N atoms.