PROBLEM TO BE SOLVED: To provide a foundation for facility installation of a deck bed roof that prevents the load of facilities from being placed locally on a mountain part of a steel-made deck.SOLUTION: A foundation 200 for facility installation of a deck bed roof includes: a steel-made deck 10 comprising mountain top surfaces 13a and 13b, valley bottom surfaces 14a, 14b, and 14c and inclined surfaces 15a, 15b, 15c, and 15d; a roof heat insulation material 91; a lower member 20 which is installed on a deck bed roof 100 having a roof water-proof sheet 92, and fitted to the valley bottom surface 14b of the steel-made deck 10 between a pair of beams 90; an upper member 40 which is installed on the lower member 20, and penetrates the roof heat insulation material 91 and the roof water-proof sheet 92; and a water-proof reinforcement sheet 93 which is installed over a part of the upper member 40 and a part of the roof water-proof sheet 92. The upper member 40 is provided with facility installation means 47.
