To provide a vehicle driving state monitor capable of accurately grasping vehicle behavior with a small arithmetic amount unlike before, and capable of precisely deciding a driving state.

By time-integrating a yaw rate YR detected for a monitoring time T1, plural yaw angles YA(i) are calculated (S12). A correlation coefficient COR between the yaw angles YA(i) and detection time t(i) corresponding to the yaw angles YA(i) is calculated (S13). When a lane change is not performed with the correlation coefficient COR not more than a threshold value CORLIM, it is decided that a driving state is abnormal, so that an alarm is given (S14, S15, S16).