Abstract
A driver's heart rate rises when a driver on a stationary driving simulator performs a lane changing maneuver. We presumed 4 kinds of factors, steering load, visual stimulus, mental pressure and mental disturbance, affecting the heart rate fluctuations and then we tried to separate the heart rate fluctuations by respective factor. A part of the rise in heart rates which is considered to be affected by the "mental disturbance" caused mainly by vehicle's stability, was separated and determined as the evaluation value. Comparing this value, we have successfully evaluated the vehicle's handling characteristics fairly accurately.