The effects of steaming and roasting temperature and time on mallotus bark ( Mallotus japonicus ) tea leaves were investigated. The characteristics we analyzed were color tone, soluble polyphenol content, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical capture activity. We observed that roasting had greater effects on tea leaves than did steaming. We concluded that the suitable roasting temperature was below 200°C for ensuring ideal soluble polyphenol content and DPPH radical capture activity. For optimal color fading, the suitable roasting temperature was below 150°C.