Abstract: A humidifier with automatic humidification control using a humidity sensor to detect surrounding humidity and a central processing unit to control on/off of an electric fan and a nebulizer (for example, ultrasonic oscillator) of a humidification unit, enabling the electric fan and the nebulizer to automatically perform a humidification action when the humidity detected by the humidity sensor is below a predetermined low level or to stop the humidification operation when the humidity detected by the humidity sensor surpasses a predetermined high level. As the electric fan and the nebulizer do not keep working continuously, the invention can save energy consumption and reduce component wear and prolong the lifespan of the humidifier.