To provide an installation method for a heliostat capable of obtaining a concentrating power generation system capable of obtaining high light concentration efficiency by arranging heliostats at optimal locations in terms of light concentration efficiency, when constructing a concentration power generation facility for concentrating solar light to a receiver installed at an upper part of a solar tower by a plurality of heliostats, and using the concentrated solar energy to perform solar heat power generation or/and solar power generation.

On the basis of an installation location of a receiver identified from a latitude, a longitude, and height from the ground, height of a mirror body of a heliostat, and an orbit of the sun, a cosine effect map of the heliostat in a periphery of a solar tower is obtained, and the heliostat is preferentially arranged in an area where a cosine effect is high on the cosine effect map.