To provide a building panel retro-installation method that prevents reduction in strength of concrete and degradation in aesthetics of a building panel and improves execution.

A bolt receiver 11 having an internally threaded portion 3, a resistant portion 4 extended substantially perpendicularly from a closed bottom portion thereof, and a flange portion 6 extended substantially perpendicularly from an upper portion of the internally threaded portion 3 is embedded in a surface of concrete 21. Marking means 16 are attached to the bolt receiver 11. With the position of the bolt receiver 11 marked on a building panel 24, a through hole 26 is drilled in the marked position. A bolt 27 is inserted from the surface of the building panel 24 and precisely threaded into and united to the bolt receiver 11.