In this study, we experimentally investigated the effect of contact softness between a robot fingertip and an object on frictional force during grasping of an object. A soft fingertip is generally considered that it produces high friction. However, in our previous experiments with silicone and duralumin, we were able to obtain high friction from a stiff fingertip. It was difficult to control stiffness of the fingertips used in this experiment minutely. Thus, we developed a softness-changeable fingertip by temperature control. In this study, we investigated the relationship between the static frictional force and fingertip stiffness when the developed fingertip is in contacts with an acryl plate. And the experiment showed that the same result that high stiffness fingertip produces high friction.