To provide an anchor base whose angle can be easily adjusted by using a simple constitution.

This anchor base 1 is composed of a fixed plate 2 which is installed on a bearing plate 6, and a rotating plate 3 which is rotatably superposed on a top surface of the fixed plate 2; the fixed plate 2 and the rotating plate 3, wherein circular holes 4 are opened in the central parts of discs, are formed in such a manner as to be gradually inclined from one end to the other end in a side view; a fitting protrusion 10, which is provided around the circular hole of the undersurface of the rotating plate 3, is fitted into the inside of the circular hole 4 of the fixed plate 2; and at least one latching protrusion 8, which is provided on the peripheral surface of the fitting protrusion 10, is latched into a latching groove 9 which is provided at each proper interval along a peripheral edge of the circular hole 4.