To provide a surface treating device capable of performing surface treatment small in intra-plane fluctuation or the like, to provide an electron emitting element having excellent electron emitting characteristic, to provide an electron source high in uniformity, to provide an image forming device having excellent displaying quality and high in uniformity, and to provide the method capable of producing them in a high yield.

This surface treating device for surface-treating a substrate 200 to be treated, which is arranged in a treating vessel 202, by supplying a treating agent in a gaseous state is provided with a treating agent supply means 203 to the treating vessel 202, a treating agent introducing port 204, a treating agent exhausting port 205 and a treating agent exhausting means 206 from the treating vessel 202 and the treating agent introducing port 204 is movably formed to change the discharging direction of the treating agent.