The printing method of the thermal transfer printer is to push an ink ribbon that is heated and melted by a thermal head to a printing paper, and transfer the ink to desired positions on the paper. Thus it is important to place the heater of the thermal head at the position where the contact pressure becomes most high. The visco elastic properties of the ink, PET and platen rubber were measured with a rheometer. The contact pressures on the thermal head were calculated by FEM. The contact pressures under consideration of visco elasticity were different from those calculated by elastic analysis. We designed the thermal print head by using this analytical result, and confirmed the print characteristic.