The manufacture of activated carbon from oil palm frond waste using an ultrasonic wave activator has been successfully carried out. The carbonization process was carried out at a temperature of 250ºC for 90 minutes. Activation with ultrasonic waves (35 Watt, 40 KHz) for 30 minutes was able to increase the iodine number from 330.06 mg/g to 799.14 mg/g and was in accordance with SNI No.06-3730-1995. FTIR spectra show that the activated carbon of oil palm fronds has a functional group –OH at wave number 2900-3200 cm-1, C=C at wavenumber 1500-1600 cm-1, C-O at wavenumber 1200-1250 cm-1. The results of the adsorption test on Rhodamine B dye showed that the activated carbon produced had an optimum absorption capacity of 9.04 mg/g at a concentration of 400 ppm for 90 minutes. Studies show that the adsorption isotherms absorption mechanisms tend to follow the Freundlich equation with a correlation coefficient (R2)= 0.9861.