PURPOSE: To apply a circuit body in narrow-cord arranging parts in automobiles, apparatuses and the like and to avoid loss of flexibility even at high temperature by providing conductor circuits on elastic rubber substrates which are bent in a wave pattern and can be expanded and contracted freely.

CONSTITUTION: Conductor circuits 1 comprising copper foils, copper twisted wires and the like are arranged in parallel on a strip-shaped flat conductor 2. Strip-shaped unvulcanized rubber substrates 3 and 3 are overlapped on the upper and rear surfaces of the conductor 2. Thus a flat circuit-body pattern 4 is formed. The flat circuit-body pattern 4 is compressed and heated with a pair of hot press metal moldes 5 and 5 having corrugated machining surfaces 5a from the upper and rear surface sides. Vulcanization 6 is performed on the unvulcanized rubber substrates 3 and 3. Thus a flexible circuit body 8 in an elastic continuous wave shape 7 is formed. Therefor the flexible circuit body which can be applied in narrow-cord arranging parts in automobiles, apparatuses and the like and has excellent bending property without loss of flexibility at high temperature can be obtained.