The relationships between tumor score and peroxidase activities of tomato stems infected with Agrobacterium tumefaciens strain A6Kl, B6, T372 11BNV6, 11BV7 and wounded stem as a control were examined in relation to crown gall tumor development on purpose to study the lignification of tumor tissue which is affected to the development of crown gall tumor. As the previous paper has been mentioned the fact that the induction of tumor tissues were inhibited or limited in the lignified stem of host plant. It was presumed that the activities of peroxidase related to the development of lignification were decreased during the period of tumor development. But the experimental result in this experiment shows that the peroxidase activities of crown gall tumor-tissues infected with the A. tumefaciens strains which are already known as virulent are increasing during four weeks, however, in the strain 11BNV6 and wound the peroxidase activities are decreasing on the second week after the inoculation of the bacteria strains. These results could be explained on the basis of that possible regulatory agents of lignification which were accumulated in tumor tissues, IAA, ascorbic acid, glutathion(GSH) and caffeic acid esters, were postulated to act as antioxidants which has been suggested by Stafford. Total nitrogen contents in relation to crown gall tumor development were determined for the detection of protein synthesis related to the enzyme activities which are increasing in the time of plant growth. Generally six groups are contained the largest amount of nitrogen on the second week after the inoculation of the bacterium. Comparing to the tumor score, it is presumed that the all of enzyme activities including peroxidase in tumor tissues are increasing from the second week through the third week after the inoculation of bacterium and the protein synthesis is stimulated under the most appropriated temperature during the above periods.