BICYCLE SECURITY ALARM DEVICE

A bicycle security alarm device is provided. The device includes a battery, a control chip, an alarm unit and a sensor mounted on a bicycle front fork. when a thief moves or rides a bicycle, the sensor detects the vibration of the bicycle and transmits a detection signal to the control chip. The control chip transmits an alarm signal to the alarm unit and operates the alarm unit. The alarm unit emits sound to attract the attention of people around.