A driving assist device includes a driver state detection unit for detecting an inattentive state as a driver state, an alerting unit for altering the driver upon detection of the inattentive state of the driver, a driving operation unit for being operated by the driver for driving operations; and a driving state switching unit that switches at least one of the driving operations in an automated driving state to a manual driving state when the driver's operation of the driving operation unit is detected during the automated driving state of the vehicle. When at least one of the driving operations in the automated driving state is switched to the manual driving state by the driving state switching unit, the driver state detection unit detects whether the state of the driver is an excited state. When the excited state of the driver is detected, the alerting unit alerts the driver.