The quality characteristics of cheonggukjang containing Phellinus linteus extracts (PLE) and its cytotoxicity in Hep-2 and SK-MS-cells were investigated. Cheonggukjang containing 0.3% PLE showed the highest protease activity ($7^{th}$ aging day). The reducing sugar content and the amylase activity of cheonggukjang supplemented with 0.3% PLE increased immediately on the 1st aging day, and decreased slightly until the $15^{th}$ aging day. All samples showed an increase in the amino-type nitrogen content. The dominant volatile compound detected using chromatography-mass spectrophotometry was 2,5-dimethyl pyrazine with the highest peak area value of 17.36% observed in cheonggukjang containing 0.3% PLE ($3^{rd}$ aging day). Cheonggukjang containing 0.3% PLE exhibited the best taste and acceptability with the least unpleasant odor. Cheonggukjang supplemented with PLE had a higher antitumor activity against SK-MES-1 and Hep-2 cells than a control. Hep-2 cells treated with a 10 mg/mL extract of cheonggukjang containing 0.3% PLE showed the highest growth inhibition rate of 84.74%.