CLOSED EYE DETERMINATION DEVICE

A closed eye determination device includes an eye opening degree detection unit that detects a degree of eye opening of a driver from each of a series of face images of a driver in time series in a latest certain period of time being acquired by a driver monitor camera, a local minimum value extraction unit that extracts a local minimum value of the degree of eye opening from a change in time series of the degree of eye opening in the certain period of time, a reference lower limit value-setting unit that sets, as a reference lower limit value of the degree of eye opening, a local minimum value in order corresponding to a blinking number of the driver in the certain period of time in order from the smallest local minimum value among local minimum values of the degree of eye opening in the certain period of time, a threshold value setting unit that sets a closed eye determination threshold value, based on the reference lower limit value, and a closed eye determination unit that determines that an eye of the driver is closed when the degree of eye opening detected from an image acquired by the driver monitor camera after the certain period of time is less than or equal to the closed eye determination threshold value.