Patent ID: 8577566

Claim:
A driving instability determination device comprising: a running state acquisition section that acquires running state data pertaining to at least one of an operation state of a driver operate driving operation unit and a vehicle state; a running state distribution computing section that computes a first running state distribution of a first time range and a second running state distribution of a preset second time range based on the running state data acquired by the running state acquisition section, the first time range being longer than the second time range; an operation instability determination section that compares the first running state distribution and the second running state distribution computed by the running state distribution computing section to determine a driving instability; and a driving state determination section that determines whether a current driving state is a prescribed driving state, which is estimated to degrade reliability of the running state data acquired by the running state acquisition section, based on at least one of the driving state of the driver operate driving operation unit, the vehicle state and vehicle periphery information, the running state distribution computing section being configured to exclude the running state data in a period that the prescribed driving state is determined to exist, and then compute at least the second running state distribution among the first running state distribution and the second running state distribution.