We have successfully grown MnAs/GaAs/MnAs ferromagnet/semiconductor trilayer heterostructures on GaAs(111)B substrates by molecular beam epitaxy. The epitaxial orientations of MnAs and GaAs are (0001) and (111), respectively, as expected. It was found that epitaxial monocrystalline GaAs can be grown on the As-rich (3×2)-(0001) MnAs surface. Cross-sectional images by transmission electron microscopy showed that the trilayers are formed as intended with fairly smooth and atomically abrupt interfaces. Double-step features were observed in magnetization characteristics due to the difference in coercive force between the top and bottom MnAs layers. The interlayer coupling was small when the thickness of the GaAs spacer layer was 5–10 nm.