PURPOSE: To facilitate installation of an apparatus to a member and improve the degree of installation freedom by installing a member mounting surface of a base board to a prescribed member after installing an apparatus mounting body for installing the apparatus to a positioning part of the base board which can be deformed.

CONSTITUTION: When installing an apparatus 4, a semi-spherical projecting part 9 formed at the lower surface of the plane 5 of an apparatus installation body 2 is fitted in a semi-spherical recessed part 13 formed at the upper surface 3a of a base board 3. A bolt 14 is passed through a hole 15 and a through hole 10 to be tightened to a nut 16 for installing the apparatus installation body 2 to the base board 3. The apparatus 4 is positioned between both vertical parts 6 of the apparatus installation body 3, and the apparatus 4 is installed to the apparatus installation body 2 through a hole by a screw 8. The base board 3 is installed to a dashboard 17 or the like by a double-faced tape 18 or the like. Even if the dashboard 17 has curvature and the base board 3 formed from resin is deformed according to the culvature, it is thus possible to position the apparatus installation body 2 which is brought into spherical contact with the base board 3 at a prescribed position accurately.