Abstract: A wake-up device including a first flexible headband formed with a battery chamber, a second flexible headband, first oscillating means connected with an end of the first flexible headband, second oscillating means connected with an end of the second flexible headband, a first connector connected with the first oscillating means, a second connector connected with the second oscillating means, wakening means mounted between the first and second connectors, the wakening means including a balance switch, an electronic circuit connected with the balance switch, and a loudspeaker connected with the electronic circuit, whereby when the user feels tired and nods his head, the wakening means will actuate the oscillating means to oscillate and the loudspeaker to produce warning signal.