An electron source or electron beam apparatus comprises an electron-emitting device and a shield member disposed above the electron-emitting device. The electron-emitting device generates an electric field component, when energized, that is parallel to a substrate surface on which the electron-emitting device is disposed, while the shield member has an aperture which allows electrons emitted from the electron-emitting device to pass therethrough, but blocks off charged particles flying toward the electron emitting device.