An in-vehicle monitoring device is configured to monitor an interior of a vehicle with reference to sensor information from a living body detection sensor. The in-vehicle monitoring device includes: a sensor information acquisition unit that acquires the sensor information from the living body detection sensor; a visual recognition information generation unit that generates visual recognition information indicating at least one of a detection range and a detection accuracy of the living body detection sensor with reference to the sensor information acquired by the sensor information acquisition unit; and a visual recognition information output unit that outputs the visual recognition information to a display device.