To realize the inexpensive and easy execution through combination of cement products and steel products by keeping holding plates consisting of a strip-like rigid plate approximately parallel to each other by a space holding material large in compression strength, and charging a plate-like wall material in a semi-cylindrical space between an inner surface of an edge of the holding plates and an inside surface of the space holding material.

A space holding material 3 formed of a same material as holding plates is placed between upper and lower holding plates 21 of a semi-cylindrical holder 2 formed of a super-thick galvanized steel plate, and an extruded cement plate 10 is inserted in a charging space 4 surrounded by the upper and lower holding plates 21 a holding plate 31 of the space holding material 3, and an opening. Upper and lower locking claws of the holder 2 are hooked and fixed to a locking edge provided on each edge of the extruded cement plate 10, a wedge is driven in a gap between a back side of the extruded cement plate 10 and the holding plate 31, and the extruded cement plate 10 is fixed to the holder 2 to form a wall surface forming member 1. The wall surface forming members 1 are stacked to constitute a vertical wall body, and a steel pipe is driven into a through hole in the holding plates 21 to the ground to reinforce the wall body.