Author studied the changes of experimental bite marks using a special apparatus which was equipped with adults human resin dental model(in accordance with the time elapsed). The experimental bite marks were made in the forearm of 20 healthy men and in the buttock of 10 Durac pigs with various pressure. In making the experimental bite marks, the left forearm was pressed with a load of 70kgs and 130kgs for 3 seconds, and 5 of the 10 pigs were sacrigiced immediately after making the bite marks. Through visual examinations, photographs and rubber base impressions of bite marks, following results were obtained : 1. The durations of measurable indentation of the experimental bite marks in the forearm of living human subject were depended upon the degree of the pressure and the length of the pressure time applied in making the bite marks. 2. As a physiological responds to a physical stimulus of biting, indentation, bruising, edema and subepithelial bleeding were observed in the experimental bite marks in the forearm of living human. And the experimental bite marks in the buttok of pigs which were sacrificed immediately after making the bite showed only indentation and subepithelial bleeding in addition to postmortem changes. 3. The duration of measurable indentation of the experimental bite marks in the buttock of pigs which were sacrificed immediatly after making the bite were much longer than those of the living pigs. 4. All of the measurements of the experimental bite marks were not matched completly with those of the model which was used in making the bite marks.