PURPOSE: To achieve a prevention of napping by temporary use, which enables the prevention of traffic accidents, drop in efficiency of labor working, accident in the operation of a machine or the like, drop in efficiency of study, drop in efficiency during a meeting as caused by napping, use at any time regardless of timing, day or night, utilization by people in general at a low cost and the solving of problems in a short time with simpleness in moving, carrying and application method.

CONSTITUTION: This sleepiness preventer has a flat plate 1 made up of an external part 2 blocking a field of view and a part 3 which does not block the field of view.