In an electron source having an electron emitting member, the electron emitting member is connected to a first or second conductive member by a third conductive member which is connected to the first or second conductive member through an aperture forming in an insulating member, and such aperture has such a shape as to become narrower from an end of the third conductive member toward the other end. Such configuration avoids that the third conductive member is damaged in the connecting portion with the first or second conductive member by the thermal stress therein.