A sealing apparatus which is capable of preventing static leakage of a target to be sealed without increasing sliding resistance with respect to a shaft, and a surface processing method of a disk member of the sealing apparatus which is capable of processing a surface of the disk member, such as a slinger, provided at the sealing apparatus. A surface processing method of a disk member of a sealing apparatus for forming a plurality of fine spiral grooves on a surface of the disk member provided at the sealing apparatus has a grinding member having a plurality of fine projections that is moved to an outer edge side while the grinding member is pressed against the surface of the disk member which relatively rotates around an axis, and the sealing apparatus includes a slinger at which a plurality of fine spiral grooves are randomly formed on another side surface of a flange portion.