The Purpose of this study was to investigate dyeing properties and color fastness of Ainus firma sieb. et Zucc. Fruit, according to dyeing temperature, dyeing time, dyeing concentrations and various mordants. The results were as follows ; 1. The dyeabilities of the natural colorants extracted from Alnus firma fruit were investigated under various dyeing temperature, dyeing time and dyeing concentration. As a result, the optimum dyeing temperature, time and concentration of silk fabric with Alnus firma fruit were $60^{circ}C$, 60min and 100％(o.w.f.) respectively. 2. Alnus firma fruit extract dyed reddish purple (RP hue) on the Fe-mordanted silk fabric. In the case of other mordants, silk fabrics dyed yellow (Y hue). 3. Generally, the light color fastness was relatively fair in the silk fabric dyed with the Alnus firma fruit and Fe mordant. The washing color fastness of color change of silk dyeings mordanted with Al, Sn showed 4 grade. However, the dry cleaning color fastness of the silk fabric was fastness was excellent. The rubbing color fastness showed 4 grade at the most of mordants except Cu.