The purpose of the present invention is to improve the estimation accuracy in the estimation of a stressed condition of a driver.Blood pressure values (P) of a driver are recorded, and a deceleration starting time point (tg) when a running vehicle starts to decelerate and is stopped is detected. Blood pressure values (P) recorded in a biological information recording section (21) within a predetermined time period before the deceleration starting time point (tg) are referred, and a pre-deceleration blood pressure value (Pb) that is a representative value for the referred blood pressure values (P) is extracted. Blood pressure values (P) recorded in the biological information recording section (21) within a predetermined time period after the deceleration starting time point (tg) are also referred, and a post-deceleration blood pressure value (Pa) that is a representative value for the referred blood pressure values (P) is extracted. The pre-deceleration blood pressure value (Pb) and the post-deceleration blood pressure value (Pa), both of which are extracted in a biological information extraction section (23), are compared with each other to thereby estimate the stressed condition of a driver before the deceleration. That is, it is estimated that the larger the difference (ΔP) between the pre-deceleration blood pressure value (Pb) and the post-deceleration blood pressure value (Pa) the worse the stressed condition of the driver before the deceleration.La présente invention vise à améliorer la précision destimation dans lestimation dun état de stress dun conducteur. Des valeurs de pression sanguine (P) dun conducteur sont enregistrées, et un instant de début de décélération (tg) auquel un véhicule en déplacement commence à décélérer et est arrêté est détecté. Des valeurs de pression sanguine (P) enregistrées dans une section denregistrement dinformations biologiques (21) dans une période de temps prédéterminée avant linstant de début de décélération (tg) sont prises c
