  We report on the scanning tunneling spectroscopy experiments on single
crystals of IrTe$_{2}$. A structural supermodulation and a local
density-of-states (LDOS) modulation with a wave vector of $q$ =
1/5$\times$$2\pi /a_{0}$ ($a_{0}$ is the lattice constant in the $ab$-plane)
have been observed at 4.2K where the sample is in the monoclinic phase. %We
cannot find an energy gap emerging reproducibly.% on the region where the
supermodulation resides. As synchronized with the supermodulation, the LDOS
spatially modulates within two energy ranges (below -200 meV and around -100
meV). We further investigated the effect of the local perturbations including
the antiphase boundaries and the twin boundaries on the LDOS. These
perturbations also modify the LDOS below -200 meV and around -100 meV, even
though the lattice distortions induced by these perturbations appear to be
different from those by the supermodulation. Our results indicating several
microscopic structural effects on the LDOS seem to offer crucial keys for the
establishment of the microscopic model describing the parent state.
