An angle-adjustable aroma diffuser includes a housing defining opposing first opening and second opening, a aroma container mounted in the housing, a resistor attached to the bottom side of the aroma container, an aroma device put in the aroma container, and an electric plug pivotally coupled to the second opening of the housing and electrically connected with the resistor and connectable to an external power socket for conducting electricity to the resistor to produce heat so that the aroma container can transfer produced heat to the aroma device, causing the aroma device to give off a pleasant smell.