A charged particle beam lens includes a first electrode on a downstream side and a second electrode on an upstream side in a travelling direction of a charged particle beam. Each of the first electrode and the second electrode has a first through hole formed therein, through which the charged particle beam passes. The second electrode further has a second through hole formed therein, through which the charged particle beam does not pass. A distance defining member is provided between the first electrode and the second electrode such that the first electrode and the second electrode are spaced away from each other. A gap is surrounded the first electrode, the second electrode, and the distance defining member, wherein both the first through and the second through hole communicate to the gap. A third through hole passes through the first electrode and the second electrode in the travelling direction of the charged particle beam, and the third through hole is provided outside of the gap and does not communicate to the gap.