PROBLEM TO BE SOLVED: To provide means for enabling electron emission at a lower application voltage.SOLUTION: An electron source 10 includes a carbon support 3, on its surface 3a of which a carbon nano structure 5 is formed, and a foil-like body 7 for applying an electric field to the carbon nano structure 5. The foil-like body 7 has a first surface 7b attached to the surface 3a of the carbon support 3, and a second surface 7c positioned on a side opposite to the first surface 7b with respect to a thickness direction of the foil-like body 7. The second surface 7c and the carbon nano structure 5 are insulated from each other. A voltage is applied between the carbon nano structure 5 and the second surface 7c so that the carbon nano structure 5 and the second surface 7c respectively assume a negative potential and a positive potential, thereby causing electrons to be emitted from the carbon nano structure 5 through many through holes 7a.SELECTED DRAWING: Figure 1
