For the development of receptor molecules that can precisely recognize saccharide molecules, several phenylboronic acid derivatives that can act as “saccharide interfaces” have been synthe sized. These boronic acid derivatives can bind mono- and/or di-saccharides even in an aqueous media and give some physical signals such as circular dichroism (CD), fluorescence spectra, and so on. In this paper, we explain the complexation abilities of boronic acids with mono- and di-saccharide molecules and the “read-out” mechanism by CD or fluorescence spectra