Silk fabrics were treated with O₂, N₂, and H₂ plasmas for deep dyeing and good color fastness to rubbing. C.I. (Color Index) Reactive Black 5 was used as a dye, and color deepness was evaluated by total K/S. All plasma-treated silk fabrics showed weight loss, especially by O₂ plasma. Total K/S of dyed silk fabrics treated at 60 Pa of all plasmas was improved greatly. Total K/S increased with increasing plasma treatment time, weight loss of the fabrics in the treatment, and dye concentration in dyeing. They gained greater total K/S even dyed in 6% of dye concentration compared with untreated one dyed in 10%. Color fastness to wetrubbing of silk fabrics was not improved by plasma treatment. However, most of them were still within the level for commercial use.