PURPOSE: To obtain the subject fiber suitable as a substrate for printed boards, etc., by respectively and separately melting a thermoplastic polyether imide and a main chain type liquid crystal resin, joining both so that the main chain type liquid crystal resin may be present in a fibrous form in the polyether imide and discharging both the joined components from a spinneret.

CONSTITUTION: The objective fiber, obtained by respectively and separately melting a thermoplastic polyether imide (preferably having a structural formula expressed by formula I) and a main chain type liquid crystal resin [preferably having a structural formula expressed by formula II (n1≥70), etc.], joining both so that the main chain type liquid crystal resin may be present in a continuous fibrous form (preferably ≥10 fibrous substances having ≤10μ diameter are present in the cross section) and discharging both the joined components from a spinneret and having at least the surface layer composed of the polyether imide at (10/90) to (80/20) weight ratio of the polyester imide/main chain type liquid crystal resin.