Seat cushions are considered as one of the important factors influence the seating comfort. In the automotive seat cushions, flexible polyurethane foams have been widely used due to the cushioning performance. Automotive seat designers are paying more attention to the improvement of seat cushion properties. This study introduces an automotive seat that uses an air-mat in the seat cushion along with polyurethane foam. The air-mat can be adjusted with its internal air pressure. The objective of this paper is to examine air-mat seat pressure level on seating comfort. Vibration experiments have been performed on the BSR simulator with random vibration. Tri-axial accelerometers were used to measure vibration at the foot and hip. All measured vibration were about the vertical direction (z-axis). The whole-body vibration exposure parameters (weighted root-mean-square (RMS), vibration dose value (VDV), transmissibility (SEAT value)) were calculated per ISO 2631-1 standard. The air-mat internal air pressures considered were 0.017, 0.035, 0.053, and 0.07 MPa. Twelve healthy individuals who had more than ten years of driving experience participated. The participants were grouped into four weight groups were ~45 kg, 60-70 kg, 70-80 kg, and 90-100 kg. Results showed that weighted RMS, VDV, and SEAT value decreased with increased internal air pressure level for 45 kg weight group. However, a different trend of results observed for other weight groups. The possible explanation could be hip muscle characteristics includes muscle thickness, muscle strength, fat (i.e., damping effect). This paper will discuss the seat development, seating comfort evaluation method, results, and suggestions.