DRIVING STATE MONITORING DEVICE, DRIVING STATE MONITORING SYSTEM, DRIVING STATE MONITORING METHOD, AND RECORDING MEDIUM

A driving state monitoring device includes: an acquisition unit that acquires line-of-sight information indicating a line-of-sight of a driver and driving state information indicating a state of driving by the driver; a calculation unit that calculates a line-of-sight range of the driver in a predetermined driving state based on the line-of-sight information and the driving state information; and a determination unit that determines an insufficient visual observation range based on a recommended line-of-sight range and the line-of-sight range of the driver, the insufficient visual observation range being a range in which visual observation by the driver is insufficient, the recommended line-of-sight range being a line-of-sight range recommended for the predetermined driving state.