The invention provides an on-vehicle situation detection apparatus and method. The on-vehicle situation detection apparatus may include a detection unit to identify a driver and acquire driver status data and data about vehicle driving information or vehicle surrounding obstacles, a driving pattern learning unit to learn and store a driving pattern of a driver, based on the data acquired by the detection unit, a weighted value determination unit to determine a weighted value assigned to the information data acquired by the detection unit, based on the driving pattern learned by the driving pattern learning unit, a determination unit to determine a safe driving state of the driver, based on the data to which the weighted value determined by the weighted value determination unit is assigned, and a warning unit to warn the driver when the driver is determined to be not in the safe driving state. The on-vehicle situation detection apparatus and method determine whether the driver is driving safely by knowing mental and physical states associated with vehicle driving or vehicle operation by the driver, and guide, if determining that the driver is not in a safe driving state, the diver to drive safely by displaying warning, giving warning sound, reminding the driver by vibration, forcibly controlling the vehicle or other methods so as to protect the driver.