In an effort to identify quantitatively historical drought conditions, and to evaluate their temporal and spatial variability, two commonly used drought indices, the standardized precipitation index. SPI by McKee and the Palmer drought severity index. PDSI were calculated from 54 meteorological stations. SPI was evaluated {or different time scales. 3 to 48 months. As the computational spans for SPI increase from 3 to 48 months the frequency and intensity of drought decrease, but the duration of drought increase. When monthly and ten-day PDSls were compared, the frequency and duration of drought were almost equal and the intensity of drought differ slightly. The three month SPI has the advantage to detect the drought resulting from short-term shortage of rainfall, while PDSi had the advantage to detect the state of drought resulting from cumulated shortage of rainfall. The period-frequency spectrum analyses at Kangnung station showed that the maximum value of relative frequency was 24.4% when the period was 5.2 months, and the 6 month SPI has most similar trends to PDSI.