A ceramic insulated wire has a conductor core of copper or copper alloy, a stainless steel layer around the conductor core and a chromium oxide film (2A) around the stainless steel layer. The chromium oxide film (2A) is surrounded by an outer ceramic insulator formed by a vapor deposition method. Cladding the conductor core with stainless steel is done by inserting the core lengthwise into a stainless steel pipe, plastically working the resulting composite body to provide a desired size, and oxidizing the stainless steel which contains sufficient chromium for the formation of the chromium oxide film to have a thickness within the range of 10 nm to 1000 nm. The outer ceramic insulator formed by vapor deposition is made of Al.sub.2 O.sub.3, SiO.sub.2, AlN and Si.sub.3 N.sub.4 which provide an excellent heat resistance while the chromium oxide film substantially increases the bonding strength.