A humidifier with regular addition of fixed quantity of essential oil comprises a main body, and a water storage bucket assembling with the main body. The main body comprises an opening located on one side, an inner casing corresponding to the opening, and a peristaltic pump provided on a side of the inner casing not facing the opening. The inner casing defines an essential oil bottle accommodation space communicating with the opening, and the essential oil bottle accommodation space is provided for disposing an essential oil bottle storing an essential oil. The peristaltic pump is controlled by the main body, thereby fixed quantity of essential oil is supplied regularly and quantitatively by the humidifier without dismounting the water storage bucket. Thus, fragrance is kept in atomizing air continuously to solve the problem of the conventional humidifier that fragrance merely exists when the essential oil is added initially.
