To prevent electrocorrosion of a steel pipe electric pole due to a stray current by inserting an insulating pipe having a bottom cover into a longitudinal hole provided underground, vertically providing the steel pipe electric pole used for a signal pole, etc., in it, filling mortar in a margin and fixing it.

At the time of erecting a steel pipe electric pole, etc., to provide along an electric car rail, an insulating pipe 4 made of vinyl chloride and furnished with an insulating bottom cover 3 is inserted into a longitudinal hole 2 provided underground by providing a clearance 7. In this case, the insulating pipe 4 is fixed by driving a resistance plate 9 underground in the outer periphery of the insulating pipe 4 and forming a triangle by connecting each of the resistance plates 9 on their end parts to each other. Thereafter, a steel pipe electric pole 5, the insulating pipe 4 and a resistance plate 10 are integrated and fixed underground by filling quick drying mortar 8 in the clearance 6, 7 after inserting the steel pipe electric pole 5 in the insulating pipe 4 by providing the clearance 6. Thereafter, it is devised not to flow a stray current to the steel pipe electric pole 5. Consequently, it is possible to prevent electrocorrosion of the steel pipe electric pole 5.