Three methods were used to determine the sublimation and condensation at Mizuho Station in 1977--1978, that is, direct observations with an evaporimeter filled with ice and repeated measurements of offset stakes and indirect estimation using an empirical formula derived from meteorological parameters. A comparison of three methods shows satisfactory agreement, especially in the weekly average of sublimation in the 1977--1978 summer, while condensation is insignificanlty small. Condensation prevailed from the middle of April to the middle of September and sublimation in the remainder of 1977. The annual amounts of condensation and sublimation in 1977 are estimated to be 0.6 g cm-2 and 5.4 g cm-2 respectively. The daily amount of sublimation showed its maximum of 92 mg cm-2 on December 22,1977, at the summer solstice. The annual amount of sublimation much affected the annual net accumulation of 5.8 g. The sublimation and condensation contributed in the formation of glazed surface consisting of multilayered ice crusts. This glazed surface is representative in the katabatic wind region in Mizuho Plateau, and the structure of the ice crust reflects the mass balance due to sublimation and condensation on both sides of the crust. Sublimation rate varies with the direction of the sloping faces of sastrugi, being the maximum on the north-facing slope, which receives the maximum solar radiation.