Abstract: A thermal field emission cathode comprises a needle-like electrode of single crystal tungsten having an axis direction of <100> provided with a coating layer of zirconium and oxygen; a heater for heating the needle-like electrode; a suppressor electrode; and a supply source for supplying zirconium and oxygen having zirconium of not less than 3.0.times.10.sup.-6 g and not more than 10.times.10.sup.-6 g by weight to the coating layer disposed on the needle-like electrode in a range between a point apart from a junction of the needle-like electrode and the heater by 200 .mu.m in a direction of a distal end of the needle-like electrode and a plane including an outer surface of the suppressor electrode.