β-Cyclodextrin (β-CDx) derivatives modified with p-xylylenediamine at the 3-position, mono-3-deoxy-3-[4-(aminomethyl)benzylamino]-β-CDx (1; β-CDx-3-p-xylylenediamine) was prepared by the reaction of β-CDx-2,3-manno-epoxide with p-xylylenediamine. The circular dichroism properties of 1 are compared with those of the corresponding β-CDx derivative modified at the primary side (2; β-CDx-6-p-xylylenediamine), in the presence and in the absence of 1-adamantanamine·HCl. The results indicate that the xylylenediamine group of 2 is self-included in the β-CDx cavity, whereas that of 1 stays outside the cavity. The energy obtained by molecular modeling showed the same trend. The dependence of self-inclusion behavior of a pendant group in modified cyclodextrins on the position of modification could be a useful guide for designing cyclodextrin derivatives for various applications.