To provide a holding device of an apparatus base shelf, which is capable of surely holding a shelf of optional size independently of the size of the apparatus base even if the mounting base gets larger in lateral width.

A shelf 30 is provided on a mounting pad 10 mounted with an apparatus 12, and the shelf board holding device 40 of the apparatus mounting base 10 is used to hold the shelf 30. The shelf holding device 40 is equipped with a shelf suspension device 50 which is suspended from the top board 20 of the mounting base 10 to hold the one edge of the shelf 30, and an insertion holder 52 which inserts the other edges of the shelf 30 into the stationary part of the mounting base 10 to hold.