The traditional Korean hand-made papers (Hanji) were dyed with colorant extracted from flowers of Sophora japonica L.(pagoda tree), and the effect of various dyeing factors (mordant, mordanting method, pH of dyeing solution, etc.) on colors and K/S values of the dyed Hanji was investigated. Changing mordant affected the color of dyed Hanji. Mordanting with alum, copper acetate made the color of dyed Hanji more yellow, but dyed Hanji mordanted with $FeCl_2$ had dark olive color. The K/S value of the dyed Hanji mainly depended on the pH of the dyeing solution and mordanting method. It was found that sim-mordanting with alum was timesaving and effective dyeing method. The dyed Hanji sim-mordanted with alum had the highest K/S value at low pH (about 4).