PURPOSE: To freely vary the angle of bearing surface of an anchorage, by providing a ragged face around a pierced center in two plates which is provided with a pierced hole near the center and cut at a slant and enabling to fit to each other.

CONSTITUTION: A pierced hole 21 is bored at the center of a bearing pressure plate 10 which is constituted of the lower plate 20 cut at a specified angle diagonally at the upper face 23 and the upper plate 30 cut at a specified angle diagonally at the lower face 34 and provided with a pierced hole at the center 31. Radial protrusions and recessions 22, 32 around the pierced holes 21, 31 are provided on both lower and upper plates 20, 30 to enable the lower plate and the upper plate to fit to each other. Next, the slanting angle of the upper plate 20 and the lower plate 30 is set 5° and the number of protrusion and the recession 22, 32 is set 40 and these are fit and then shifted one by one. Then the angle is increased every 5° from 0° and when it is shifted up to 180°, it is varied up to 10° at maxmum.