The present invention relates to a method of forming a small gap using CMP and a method for manufacturing a lateral FED. In the present invention, a small gap is determined by the thickness of an oxide film, and so uniform small gaps of about 100 that have been impossible to attain with the art of prior lithography can be formed with repeatability. Prior lateral field emission devices have the problem of repeatability in forming a gap for field emission because they are fabricated by means of a thermal stress method or an electrical stress method. But if the method of forming a small gap according to the present invention is used to fabricate a lateral FED, a FED can be made that has low voltage drive and high current drive characteristics and uniform field emission characteristics.