Disclosed is a biological body state assessment device capable of accurately assessing an absentminded state of a driver. The biological body state assessment device first acquires face image data of a face image capturing camera, detects an eye open time and a face direction left/right angle of a driver from face image data, calculates variation in the eye open time of the driver and variation in the face direction left/right angle of the driver, and performs threshold processing on the variation in the eye open time and the variation in the face direction left/right angle to detect the absentminded state of the driver. The biological body state assessment device assesses the possibility of the occurrence of drowsiness of the driver in the future using a line fitting method on the basis of an absentminded detection flag and the variation in the eye open time, and when it is assessed that there is the possibility of the occurrence of drowsiness, estimates an expected drowsiness occurrence time of the driver.
