To provide an installation foundation capable of reducing labor and a cost required for installation as well as shortening a construction period.

An installation foundation 10A comprises: a metal base 16; a metal lid 17, height adjustment bolts 18, support bolts 19 and mortar 20. In the installation foundation 10A, the support bolt 19 is fixed to a metal plate 24 with a first fixation edge portion 47 of the support bolt 19 inserted through a nut 50 into a support bolt insertion hole 39 provided on the metal plate 24. A second fixation edge portion 48 of the support bolt 19 is fixed to a concrete slab 12 through the nut 51. A portion of the first fixation edge portion 47 of the support bolts 19 between an upper surface of the concrete slab 12 and the metal plate 24 is integrated with the mortar 20 placed in a space 46. The metal lid 17 closes an apex opening 27 of a metal tube 23.