Physicochemical properties of arrowroot starch, which was adjusted to 18, 21, and 24% moisture and heated at $100^{circ}C$ for 16hr, were investigated. X-ray diffraction pattern was changed from C- to A-pattern upon treatment(24% moisture). The swelling powere and solubility decreased by heat-moisture treatment. The treated sample was gelatinized at higher temperature than untreated one. Water-binding capacity was drastically increased as the moisture level was decreased. Amylograph hot paste viscosities were decreased upon treatment.