PURPOSE: To exercise synergistic effect making the best use of respective characteristics of both mica tapes by winding, on a conductor both of a mica tapes formed of mainly naturally laminated mica and a mica tape being formed of mainly synthetically laminated mica as a fireproof layer.

CONSTITUTION: The fireproof layer of a fireproof wire is formed by winding a naturally laminated mica tape 2' with one half width overlap on the periphery of a conductor 1. The fireproof layer of a fireproof wire is formed by winding a synthetically laminated mica tape 3 formed of mainly fluorine gold mica with one half width overlap on the periphery of the tape 2'. Symbol 4 represents an insulating layer of polyethylene, and 5 represents a sheath layer of polyvinyl chloride. The naturally laminated mica tape 2' is a soft naturally laminated mica 2'a, and this is made to contain silicon resin. Symbol 2'b represents a polyethylene film and both are bonded together with silicon resin.