Elucidation of the relationship between brain activity and driver behavior may assist in the development of new driver models for next-generation driving-assistant systems that adapt to drivers' individual characteristics. However, multiple regions of the brain are involved in driving, so it is first necessary to investigate the role of each region. In this paper, we examined the relationship between driving skill and parietal lobe activity. We performed experiments using a driving simulator featuring a curved course modeled on a real test course. When drivers steered around the curve, data on their driving operations and the state of their vehicle were recorded, and their cortical activity was measured using functional near-infrared spectroscopy. Subsequently, jerk, which is the derivative of acceleration with respect to time, was utilized to divide drivers into the high-skilled and low-skilled groups. We found that high-skilled drivers operated the accelerator pedal and steering wheel smoothly while steering into the curve. Simultaneously, the parietal lobe was more active in the high-skilled group than in the low-skilled group at the entrance to the curve. The parietal lobe is known to integrate sensory information from various modalities. Therefore, our findings suggest that the integration of sensory information strongly influences driving skill.