In order to produce the lower emittance electron beam, the higher field gradient must be used for the gun. From this point of view, we try to develop both of a polarized DC‐gun and RF‐gun. In case of a 200 keV polarized DC‐gun at Nagoya University, the accelerating gradient at the photocathode surface was designed to be 3 MV/m, and the dark current emitted from the SUS electrodes was suppressed below 1 nA. To increase the gradient, we tested the property of pure Titanium as a new electrode material. The tested electrode showed small dark current (∼1 nA) even at field gradient of 88 MV/m, which is as twice as higher than that of SUS electrode. Concerning the feasibility of a polarized RF‐gun, it seems difficult for the NEA surface to survive in high field gradient of 100 MV/m. Therefore, we proposed a new type of polarized electron source using two‐photon excitation method, for which it is not necessary to use the NEA surface to extract electrons into vacuum. For this method, the polarization higher than 90 &percent; was already demonstrated by the photoluminescence measurement using the bulk GaAs crystal. © 2003 American Institute of Physics