The present disclosure provides a processing method for preparing at least one sliding part of a pair of sliding parts, and includes a processing step of forming a shallow groove within a range of depth from 0.05 μm to 5 μm on a sealing face of the sliding part by irradiating an ultrashort pulse laser to a part of the sealing face where a positive pressure generation groove and a negative pressure generation groove are formed and removing part of a surface of the sealing face, wherein an energy fluence of the ultrashort pulse laser used in the processing step is 0.5 J/(cm2·pulse) to 7 J/(cm2·pulse).